An improvement over the original, but feels a bit tired
I enjoyed Doom 3, but it wasn't the most original concept in the world, and I feel that after 20 hours of that game, I'm done with Doom 3 for the rest of my life.
And playing Resurrection of Evil proved that to me. The game is an improvement over Doom 3 in every facet, except there's less emails to read, the game is more straightforward action and it is shorter. Oh and, they have the dual barreled shotgun, which I absolutely love :)
The game in some ways is actually easier than Doom 3 because of the hell powers a specific artifact you find in the intro movie gives you. So when things get hairy just activate your hell powers (which are invincibility, slowing down time, berserk) and just wreak havoc. The graphics are still some of the best in gaming, the game is a power hog to play, and the sound is very well done with some very good atmosphere.
But, really, RoE is really one dimensional, it's a roller coaster ride throughout and for me. Doom 3 was enough of that to not need any expansion. Still worth the buy though, especially if you're in love with the formula.