I havent played the 360 version, but I did play through the pc version a few times, so maybe I can shed some light here.
Yes, the game is buggy on the pc, and I hear the 360 version is worse. The game does however have a decent story, with multiple endings, four in all.
Also, this game is not a RPG. Its more like a FPS in a fantasy setting. There is little customization, and very limited gear options.
Its a fun game, and if you can pick it up cheap, its worth playing.
Someone mentioned Arx Fatalis, yea, the same people worked on this game, but Arx was far deeper and more complex. The influence is there though.