It brings tons of new features, but probably also new bugs. :) So you better keep your old 0.5.x installation still for a while too. The archive is missing a few parts too (namely the icons and the scenarios). This will be fixed with one of the next versions.
ChangeLog- Feature: Make news messages related to the industry (production) changes better configurable; you can now disable news messages popping up for industries you are not servicing (r11442)
- Feature: When sorting stations by cargo sum, only sum the cargoes that are selected in the filter (r11437)
- Feature: Show all players who have shares, not just the first two (r11435)
- Feature: Make OTTD's sprites replaceable using Action 5 and make replacing contiguous subsets of sprites in for some types possible in Action 5 (r11433)
- Feature: Allow town-bridges to be build on slopes (r11395)
- Feature: Auto-road; same as auto-rail, but for road and trams and only on X and Y direction (r11339)
- Feature: OTTD version checking for NewGRFs. This allows NewGRFs to do something different for different versions of OpenTTD, like disabling it for too low versions or loading different graphics (r11330)
- Feature: Half tile- and anti-zig-zag-foundations (r11319)
- Feature: Control-Clicking the Centre Main View button on the vehicle window allows the main viewport to follow the chosen vehicle (r11304)
- Feature: User customisable faces (r11269)
- Feature: Make more advanced rail types more expensive to build (r11265)
- Feature: Implement the "moreanimation" feature of TTDP, so we can properly support newindustries (r11228)
- Feature: [NewGRF] Add support for newindustries (r11204)
- Feature: Sort the NewGRFs by name, making searching a specific NewGRF a lot easier (r11175)
- Feature: Add possibility to show the bounding boxes of sprites using CTRL-B so one can get a better understanding of the used bounding boxes to fix the glitches that still exist. Note that showing the bounding boxes is not glitch free; it only gives you some knowledge where the bounding boxes are (r11174)
- Feature: Remove the arbitrary limit of 10 articulated parts for a vehicle (r11120)
- Feature: Autoslope, changing of slopes of tiles that already have something build on them. Does not work for tiles of houses/industries/stations that do not allow autosloping (r11107)
- Feature: Support for encapsulating files into a .tar file; you can pack all files in your data/ directory in how ever many .tar files you like, keeping the directory-structure equal to the unpacked version, and OpenTTD can handle them just like the files were unpacked (r11106)
- Feature: Allow slopes under statues (r11069)
- Feature: [OSX] Added more options for right click emulation (controlled from the interface tab in the patch window) (r10996)
- Feature: Allow building and removing tracks and signals when there is a train on a parallel diagonal track that does not interact with this one. (r10922)
- Feature: Added TileHeight to the Land Area Information tool [FS#653] (r10878)
- Feature: [OSX] OpenTTD will now pick the same language as finder is set to if no config file is found (r10851)
- Feature: Provide an infrastructure to have resizable windows that are smaller than the default window size. Useful for playing on very low resolution systems (r10704)
- Feature: Support for autosave_on_exit in the console, so dedicated servers can use it (r10658)
- Feature: Add a soft limit of 4096 "entities" in a station's waiting queue and a hard limit of 32768 so (malicious) people cannot cause a "denial of service" attack by filling cargo lists (r10555)
- Feature: Replace all the windows for Industry building by a more flexible one (r10496)
- Feature: Support for "prospecting" raw industries, i.e. you pay an amount of money and then it might (with a given chance) build a raw industry somewhere on the map (r10451)
- Feature: Automatic signal completion, enabled by pressing CTRL when dragging signals. Signals will continue following track until an existing signal, junction or station are reached. This currently replaces the existing use of CTRL-drag for changing existing signal type (r10437)
- Feature: New sign editor features including switching to previous/next sign (r10401)
- Feature: Disallow (in the GUI) the building of infrastructure you do not have available vehicles for. This means that the airport building button is disabled till you can actually build aircraft. The game itself will not disallow you to build the infrastructure and this "new" behaviour can be overridden with a patch setting [FS#669] (r10353)
- Feature: Add the possibility of automatically filling in timetables based on the times from the first (or subsequent) run-throughs (r10331)
- Feature: Option to select the "default" rail type when you start a new game or load a game. This is done either static, i.e. rail, electrified rail, monorail and maglev, or dynamic which takes either the first or last available railtype or the railtype that is used most on the map [FS#812] (r10329)
- Feature: Give a better explanation why the loading of a savegame failed and do not crash on loading savegames that were altered by patches or branches [FS#917] (r10300)
- Feature: A sticky button for the client list window [FS#885] (r10293)
- Feature: Allow double-clicking on certain places: add NewGRF window, build-vehicle and town-action (r10265, r10267)
- Feature: Loading indicator, which shows in % how full a vehicle is while loading/unloading (r10254)
- Feature: Introduce a form of timetabling for vehicles (r10236)
- Feature: [NewGRF] Add support for action 0F (town name generator) (r10211)
- Feature: Add support for personal directories on Windows. (r10182)
- Feature: Add support for anti aliased typefaces via FreeType. This is configurable for each font size in the configuration settings and requires using the 32bpp blitter and suitable fonts (r10166)
- Feature: 32 bpp sprite support and dedicated driver does not blit nor render by default. Can be overruled by user (r10121)
- Feature: Add support for articulated road vehicles (r10097)
- Feature: Allow moving of orders instead of removing them and readding them somewhere else [FS#828] (r10071)
- Feature: Replace hard coded spritecache size with a configuration option, sprite_cache_size. The default size is 2MB and the value can range from 1 to 64MB. If you experience slow-downs when scrolling the map, try increasing this setting (r10042)
- Feature: Skip to the selected order in the order list when clicking on the "skip" button while pressing CTRL [FS#760] (r10033)
- Feature: Sort the strings in server language dropdown and the town names dropdown (r10032, r10036)
- Feature: Build windows of trains, road vehicles and ships can now be sorted by cargo capacity (planes already had this option) (r10024)
- Feature: More languages flags for servers [FS#790] (r10017)
- Feature: Allow different signal types on one tile [FS#362] (r10006)
- Feature: Support for oneway roads (r9999)
- Feature: Add smooth viewport scrolling. This must be enabled with patch setting 'smooth_scroll' (r9962)
- Feature: Allow terraforming under bridges (r9950)
- Feature: Support for trams (r9923)
- Feature: Allow building new stations adjacent to existing stations by holding down control (r9905)
- Feature: Add one new zoom-out level: 8 times (r9884)
- Feature: Advanced vehicle lists a.k.a. group interface. Now you can make groups of vehicles and perform all kinds of tasks on that given group (r9874)
- Feature: Make "improved loading" a proper improved loading instead of loading one (semi-)random vehicle at a time. Furthermore fill multiple vehicles at once when there is enough cargo to do so (r9838)
- Feature: Add drag and drop removal of station tiles (r9810)
- Feature: Support for "curvature info", Action 2 for train, variable 45 (r9803)
- Feature: [NewGRF] Add action 1, 2 and 3 support for canals (r9797)
- Feature: Add the possibility to choose different road patterns for towns to use (r9779)
- Feature: Add an option to automatically pause when starting a new game (r9734)
- Feature: Add the concept of cities. A (configurable) proportion of towns can start off larger, and will grow twice as quickly as other towns (r9667)
- Feature: Add NewGRF Action 5 (Sprite Replacement) support for 2cc colour maps, airport, and road stop sprites (r9645)
- Feature: Increase cargo types from 12 to 32 and enable newcargo flag in NewGRF loader (r9638)
- Feature: Make it possible to have some control over the town growth (r9613)
- Feature: Add list_patches console command. This shows all patches along with their current values (r9565)
- Feature: Add more finer control to transparency options, including a new toolbar (r9563)
- Feature: Add support for variable snow lines in the arctic climate, supplied by NewGRF files (r9371)
- Feature: [NewGRF] Add support for newhouses (r9315)
- Feature: [NewGRF] Add support for Action 13, which allows you to translate GRF-specific texts. The translations will only be shown if you are using a language with a GRF language id and if a string has not already been set specifically for the language you are using (r9037)
- Feature: Translation dependant formatting of dates (r8906)
- Feature: If an action 7/9 leads to skipping the rest of the file, disable the NewGRF if an action 8 has not been encountered yet (r8831)
- Feature: Stop loading and disable the current NewGRF if a fatal error message in Action B is encountered. Also be more strict on the values accepted (r8830)
- Feature: Build aircraft windows will no longer show aircraft that cannot use the airport in question (r8771)
- Feature: Drive-through road stops (r8735)
- Feature: Allow upgrading bridges by building a new bridge over the top (r8567)
- Feature: Provide aircraft with vertical separation depending on their altitude and velocity (r8534)
- Feature: When linking the terraform toolbar to the build toolbars place them side by side instead of on top of each other (r8436)
- Feature: The vehicle build windows are now resizable in horizontal direction as well (r8331, r8336, r8338)
- Feature: Automatically build semaphores before a configurable date, which can be set by each network player separately (r8151)
- Feature: Increase sprite limit from 16384 sprites to 16777216 sprites (r8128, r8129)
- Feature: Add the ability to load savegames when you do not have the exact GRF files in your list. GRF files that are found based on GRF ID (but not on matching md5sum) are used instead of disabling them. This does not affect MP games, there you still need an exact match (r8106)
- Feature: Show the activated status of the GRF list after pressing 'apply' in the NewGRF window, instead of the local list (r8094)
- Feature: The station list does now remember the sort settings (r8065)
- Feature: Make it possible to override the bind address and port of a dedicated server from the command line (r7802)
- Feature: Add command line option to prevent saving of high score and configuration on exit and a console command to manually initiate a configuration save (r7801)
- Feature: Add support for tractive effort to 'realistic' acceleration (7592)
- Feature: Allow to build bridges of arbitrary rail/road combinations (including signals) (r7573)
Full Changelog at Sourceforge.net