The original SP game is very good. Warband is the multiplayer expansion and has updated the graphics as well.
It has a try before you buy system where you can play up to level 6 or so before the character is locked. You can start as many characters as you like but they all get locked on level 6 (I think) until you buy.
I believe there are a lot of youtube videos around of the gameplay.
I got hooked and spent many an hour on that game.
