Horrible game. Pre-release, me and my mates all had plans on what classes we'd play, and the roles we would fill. We played for 3 hours or so; and none of us liked it. The multiplayer consisted of 'who will reach the weapons first', and shooting skags, and then more skags, and more after that. I didn't even get half way through the singleplayer, I got too bored.
Can't speak for the DLC, but the native game was a piece of stuff.
Also note that I loved fallout 3, and oblivion.