Don't let this game fly under your radar! As good as Dragon Age: Origins!
On normal difficulty, the game is challenging, so remember to save often! But it's got all the components of a good game: puzzles, exploration, critters to kill, item fever, story, NPC chatter, mindreading (yeah, mindreading!), etc. and it effectuates them well. You play alone rather than gathering teammates, but there are options to summon or create your own party.
I finished the tutorial after about an hour, but then realized that the real tutorial--which is the whole introductory section of the game--was actually about 5 hours. The gameplay is enjoyable, long-lasting and utterly immersive. I'm playing on a fairly powerful DIY computer (with a one-year old Nvidia GTX 285), but I haven't experienced any of the bugginess other reviewers complained of, either. In the first 7 hours, I had one lockup during an area transition; no complaints since. If you can find it for 1/2 off, buy it now; even if you have to pay full price, buy it now! 400 hours later, you'll thank me.