I do agree that, at times, it does feel DLC-ish, but it's one hell if a DLC at that.
The NCR were the original protagonists/antagonists, which didn't exist in Fallout 3 due to the fact that they have a whole country between their locations. Heck, at the time of Fallout 3, they were at war with CL/BoS (can't remember which) over Hoover Dam. The BoS are mainly a tech-gathering organisation, and aren't truly 'evil' - they simply don't care about what gets in the way, things that are unimportant, and things that don't care about them. There are supposedly remnants of the Enclave around supposedly, but they have been pounded into the ground in both F2 and F3, (if said endings are canon) so I doubt they'd be back for a third helping of death and failure.
The story is better than F3 - still not brilliant, but better than F3. There were few bombs that hit the west coast, therefor there is far more vegetation than in the east, and fewer radiation pools.
