I like the idea, and the support for a relatively new digital book format, so good for you Carsten to program/realise something to handle these book files.
The only problem, and I appreciate it's only an early alpha release at this stage, is that the books I downloaded from the Free download sites, e.g.
epubBooks.com -The Woman in White by Wilkie Collins don't allow the books to be read, only a few words on sporadic pages are viewable at this stage, but as it's a work in progress I hold off on any crticism, and I am just mentioning this situation as an observation, and hope that further work on the program will bear fruit, for you, and then for all MorphOS users.
MacMini 1.5GHz,64MB VRAM, PowerBooks A1138/9 (Model 5,8/9),PowerMac G5 2.3GHz(DP), iMac A1145 2.1GHz 20", all with MorphOS v3.18+,Airport,Bluetooth,A1016 Keyboard,T-RB22 Mouse,DVD-RW-DL,MiniMax,Firewire/USB2 & MacOSX 10.4/5