I just finished the Doom 3 expansion pack, Resurrection of Evil. The final boss battle was quite frustrating, and I (sadly) had to resort to "god" mode. The level designers simply didn't put enough human souls around the final arena for use with the Artifact. Anyway, besides this disappointing boss battle, I think this expansion pack fixed a few problems with the original Doom 3:

1. The levels are a little more varied this time around (some great new locales were explored).
2. Lighting was way more acceptable; flashlight use was kept to a reasonable level.
3. A double barrelled shotgun was included. Why wasn't this in the original game?

I might play through it one more time, just to check out the environments again. Overall, it's a worthy expansion pack (which wasn't a bad buy for a mere $15). My rating? 4 out of 5.