Not as good as Fallout 3, but more challenging and dangerous. I died 8 times more in this than in Fallout 3 (mostly by deathclaws and Dead Money DLC). There are 5 times more weapons than in Fallout 3. If you get the dlcs there are a ton of weapons and about 12 different bullets, and there are different types of each bullet. Armor piercing, hollow point, magnum, and more. Its a bit overwhelming how complex it is, especially if you just want to shoot at someone. You need to see if they wear armor or not before you shoot. All the junk lying around is slightly more useful with tons of craftable items. Companions now let you go on companion quests.
2 sides are at war, and there are many more groups you can ally with or destroy. I honestly did not care much about the New Vegas Strip area. This Mr. House guy thinks that his casinos and stuff will save the world. Why the hell would I choose casinos over rebuilding the world? Some people don't make sense. Enemies will hunt you down. Deathclaws can kill you in a second, and even at level 50. What really annoyed me was how easily you can accidently betray your allies. I did not get the ending I wanted. You need to be loyal to them, or they will be ruined.

Repairing armor is stupid. Its EXTREMELY expensive and finding a copy to repair it with is rare. If you are level 50 and find nice armor that gets broken, it will cost you everything. You do get a couple places to live, but they all suck. The suite in the Strip you can get is nice, except its really dark and the music is haunting, and you can't travel right to it, you have to enter the Strip, go inside the main building, then up an elevator.
Now the DLCs. Dead Money is pretty bad. Walking near radios will eventually make you explode, so they placed them in areas where you need to run and find them asap or you die. Traps everywhere forces you to sneak all the time. And theres the holograms that cant be hurt that can kill you (light that fires lasers at you, how dumb is that). Honest hearts is a little better, but the terrain is hard to travel, and it got boring. Old World Blues is the best, but you need to listen to dialogue for 30 min. The story is very interesting, and theres lots of funny, odd, and weird sciency things (like listening to a brain masturbate by looking at you). Best house you can have is in here, and it can do a huge amount of stuff for you, including resetting certain things from the beggining of the game. Lonesome Road is 2nd best, but the guy you need to find is really confusing. The way he talks makes it hard to understand him. The area is easily the most destroyed and ruined place in the game, and theres deathclaws. Also you do not get to continue if you finish the main quest, which they let you do in Fallout 3 dlcs.