Bethesda should be ashamed of Fallout 3 after playing New Vegas. This game is what Fallout 3 should have been.
I've played a pretty good bit of the game so far and aside from some technical issues (which come on, this is a MASSIVE game, its going to be bugged up) The Mojave Wasteland is full of life and adventures, not just a desolate wasteland with metro tunnels covering 90 percent of traveling and dead ends everywhere you look. Fallout New Vegas does something Bethesda wasn't able to do, actually it does a lot of things ;].
One good thing about this game is you dont run into the same character models everywhere you go, pretty much every NPC (even the enemies) have their own unique look and face model along with their own unique voice actor. Im not saying every NPC has a different voice actor but its a significant difference from the repetitive voices we got in FO3.
Atmosphere is VERY nice too, tumble weeds, mini dust storms, skirmishes between factions and fights between wildlife.
*VERY TINY SPOILER, MINISCULE*
I was walking down the highway and a guy walks up to me, he needs help saving his girlfriend from a gaggle of geckos on the mountain. I say "Okay, Ill help you", So I go and destroy the Geckos and here comes Mr. Helpless, it turns out he just wanted to get to the stash that the Geckos were guarding.. and thats excactly what he planned to do after he killed me.
What Im trying to say here is you will run into these crazy mini adventures wherever you go in New Vegas. Anything can happen! :). It actually feels like life is going on around you as you roam around, very good atmosphere.
Factions(3 main, 5 or 6 mini), double the weapons, weapon mods, iron sights, campfires for making chems and stimpacks, armor crafting, more side missions and a longer main storyline (and much better I might add), to be honest I cant even think of all the improvements that were given to us at the moment. Despite some framerate issues and bugs that Im 100% sure will be fixed this game is definately worth picking up if your an old school Fallout fan or even a New school Fallout fan :). If you liked Fallout 3 but you felt like you needed something more or better, New Vegas is for you!