I will start by saying I'm not a fan of horror games, survival horror games, or any dark atmospheric games but that never will effect my opinion on gameplay. Playing this game on and off through the years and finally beating it not too long ago, I like it but it's nowhere near as amazing as the original games. I'm just going to start with the negatives first. Doom 3 is a great game and a great shooter just not a good Doom game. I've always said this and I'm saying it again. My friend and I just completed Doom 3 co-op for the original XBOX as well and I recently completed Doom 3 main game in the BFG edition, working on RoE and still need to play Lost Mission. So installed the original game, installed the HD mod and beat it and RoE. Not only that, pressing the elevator button in one of the Delta Labs levels causes a significant game breaking bug that will not allow you back into that elevator to proceed. Once the BFG edition came out, I took screenshots via Steam and apparently using the Steam overlay will/can cause achievements to break.
So I played Doom 3 on and off but never really beat it over the years.
I'm doing this LTTP because I recently beat Doom 3 in the BFG edition for PC.