I think this was the only release I've completed from ID, never finished the last Doom game. It was similar with the Metro 2033 ending, kind of a waste when you spend so much time playing for them to cut short.
I rarely play game, so was expecting at least something. Deus Ex is the main one I need to finish - Rage was different though for a FPS, only 1 main boss which you deal with around midway - needed a final boss/battle.