I played NV first, then went to FO3...couldn't say it was a smooth transition. The Good v. Evil was far too obvious and became bland after a bit into the main story. Also all the little things NV added. Not to say it was a bad game, I haven't played enough of it it make such a statement, but I prefered New Vegas. However I do have thoughts about the main story:
At first I did like Dad's story, how you're forced out of your home and have to make sense of it all. But then it became Help Out the Brotherhood and then I killed the Enclave in a simple sentence that somehow overloaded the supercomputer...it made no sense, it still doesn't make sense to me. It totally went downhill from there.
But what bugs me most, after reading up on F1/F2 lore and setting, and something I hadn't thought until it was brought up, HOW DID THE NATION'S CAPITAL SURVIVE DIRECT NUCLEAR BLASTS? D.C. should of been China's #1 target, NOTHING should of remained. Yet valuable technology and relics survived and most of the buildings still have four walls on them.
At least NV explains you why Vegas wasn't utterly devastated...and according to some maps (not sure if official or not) of the canceled Van Buren, most of that game takes place in Arizona/Utah...very sparsely populated areas, areas where a nuclear attack would not of been likely.