Surprisingly good, with great graphics but horrendous voiceacting.
That being said, and despite this fatal flaw, this game is fairly decent and surprised me pretty often with it's size and depth (in literal sense, the dungeons are very deep in this game). And the graphics are not bad either for a 3 year old game, it suffers though from the same problem Oblivion has, all the characters look pretty much the same and are hideously ugly and the lack of female npcs besides your sister is a bit of an mistery to me.
The combat is very similar to Oblivion, so not very good or deep, it's a clickfest and usually depends on how fast you can click you mousebutton and quaff down health potions, and just like in Oblivion bows and arrows are totally useless. Just get a chainarmour and a huge sword and you are pretty much invincible.
They are soon releasing Two Worlds Two (probably the worst title of a game in history) and I so hope they get decent actors to voice itand improve the combat. If so I might acctually give it a try.