What doesn't make sense in Fallout: New Vegas is that you almost die from a gunshot wound to the head. I can shoot someone in the face with a missile launcher and they may still live.
I've noticed this too. I shot a HUMAN thrice with a rocket launcher and he was still alive. All direct hits.
Anyways, I really loved the FO3 atmosphere but I felt like after a while, it got to be nearly TOO much - kind of lonely and monotonous. I think New Vegas is at the other extreme, it just barely passes as a post-apocalyptic wasteland. Not sure where a good balance really lies.
Either way, both the games are amazing (assuming you are willing to put up with copious quantities of glitches). If (probably 'when') Bethesda makes the next fallout, I will definitely be buying it!