Norhing really new, but still fun.
First of all, when the game originally came out, you could not have more than one game saved, and that is what was so great about the original Dungeon Siege. You could start over and try something different if you wanted to, but could still go back and play your old game if you felt like it. You could not do this at first in Dungeon Siege 2, though they have fixed that in a patch, so it seems to be alright.
Good things about the game, include that there are new spells, and weapons, and such. These things are always a welcome thing in a new game, and add more to it. Combat is pretty much handled the same was as in the original DS, though the abilities you can learn make it a little different, and even a little harder to get used to, especially when trying to handle more than one character's skill.
Overall DS 2 adds to what the original DS did, and makes for a decent game to waste some time on.