First off, you should buy this to encourage more of these come to PC. Second, it uses games for windows live which a lot of people are against. Personally it just means a little more time into getting updates and having to log in to play, I have a stable internet connection so this isn't too much of a problem. Aside from requiring some patience and a log in, there shouldn't be any problems. Third, as mentioned in the first; we need more of these games on PC. I've seen a bit here and there of the Xbox version and they are adding new content to what is already there which is awesome in addition to getting it running on PC in only a few months.
The game is an RPG that has a bit of an old feel to it. You make your character similar to in games like Fallout 3/The Elder Scrolls, where you spend points into various stats or pick a preset class. You also get a special item, word is that the Master Key is pretty good. Anyhow, as you kill things you collect souls which seem to act as both a currency and a form of experience you can spend on leveling up. However, you drop all your souls upon death and must retrieve them. You trade your souls for weapons and armor or spend them on additional stat points so that you can take on tougher challenges. I don't know enough about the story to give a fair opinion, but the combat is good. However it isn't very fast paced which some people may not like.
Again, if you don't buy this just because it uses Games for Windows Live then it could undo all the effort put into getting on PC. Just make sure to go post it on their forums or start a campaign to stop Game for Windows Live, but don't let it ruin future games for the PC.
In short: This is a good game, the flaw is Games for Windows Live. As for positives, new content is added, it's for PC, get a PC compatible Xbox Controller if you don't like the mouse and keyboard, it will hopefully be a success and more games like this will be made for PC which is good for everyone.