I was forced to use LibreOffice when my old employer's account for Microsoft Office expired.

It's... well, hard to describe fairly. Obviously it's far more powerful than most office packages (especially free ones), but it's slow and clunky, has some UI design issues (Calc cell borders are a real pain trying to do proper work) and strangely lacks the occasional simple feature while covering a lot more obscure ones. The one that bit me last week was trying to put a line break every 80 chars so an exported textfile would be readable in readers that didn't support word wrap. It just couldn't do it.

Better than nothing at worst, an excellent free office package at best, but if it's slow on an i7 with a high end graphics card, I hate to think what it'll run like on a G4.