Doom 3 was a big, big disappointment to many people. To those hardcore fans of the original who were 13-20 when the original game was released, it rocks. To the average gamer, it's a very dull game at times and frustrating too. Doom is supposed to be about running like hell, with mobs of undead chasing you exactly what doom 3 isn't, it's more about you and one or two guys duking it out with scripted assaults, etc.
Personally, I prefer Far Cry over Doom 3 and cannot stand battlefield-type games period.