Having had a little more time to fully digest the Resurrection of Evil (RoE) expansion pack for Doom 3, I've thought of a few more things worth mentioning. The more I think about it, the more negative points I can see in the expansion. Here is a brief list:

1. Frame Rates: I don't think Nerve paid near enough attention to this during development. There were a number of times when my computer nearly choked, something I never saw in the original game.
2. The Grabber: Countless people have likened the "grabber" in this game to the gravity gun from Half-Life 2. But those comments are a little too kind. The gravity gun in Half-Life 2 was way easier to use from a player's point of view, and it worked way better. RoE's grabber just isn't as fun. While it's cool to catch a demon's fireball and shoot it back, I found the weapon required a level of accuracy that I clearly don't possess.
3. Difficulty: At the "normal" level of difficulty in Doom 3, I never felt overwhelmed. This expansion was quite the opposite. Perhaps the developers chose to make it harder to create the illusion of an increased length. For me, it only resulted in frustration.