I played the demo a while back, and as much as I tried, I just couldn't get into the game...
Hmmm, yes and no. The gameplay and technical aspects are identical in the final build, but pacing and missions are much more interesting than the small portion of the demo. I didn't mind the demo, but it didn't blow me away, I quite enjoyed the full game though. I don't want to try ans sell you on something you won't like though, and if you weren't impressed by the demo then you might not like the full game any better.
My biggest gripes would probably be the lack of enemy and environment variety. The Warhammer world has a rich and detailed set of characters and worlds to draw from and I have to admit I was a little disappointed that there weren't more units, vehicles, races and settings in full game.
Having said that I thought it was a great base with which to build future sequels from. Far better than Fire Warrior on the PS2 anyway. I just hope SEGA puts the license and the devs to good use now that THQ is gone.