After spending about 2 hours with the full game, I am truly impressed. This game is like you said, a masterpiece. The only number of games I've played in the last few years where I felt a true sense of exploration are Gothic 3, Fallout 3 and now this game. Gothic 3 didn't run too well on my PC, but it was still quite good with the community patches. This game runs very well and I like the graphics style.
If you want to play a game where you can explore an interesting world and get immersed in a story, this is definitely a game you should enjoy. Try the demo for yourself and see if you like it. If you like the demo, you'll probably like the full game just as much.
1. Q6600 @ 3.2, ASUS P5Q Pro Turbo, Powercolor HD 4890 CrossFire, 4GB Mushkin DDR2-1066, 3x 24" LCD, Matrox TripleHead2Go, Audigy 2 ZS
2. Q9550 @ 3.7, ASUS P5K, Galaxy 8800GT G92, 2GB Mushkin DDR2-1066, Samsung 710N + Samsung 205BW, Audigy 2 + SB Live! 5.1 (hooked up together, really), dad's comp
3. XP-M 2500+ @ 205x11.5, Gigabyte nForce2-400, GeForce4 Ti4200, 2x512MB OCZ DDR-400 "Premier", oldie