If you look at fallout 3, it was new, it was big, and it had many choices in almost every quest.
But if you look at Fallout New Vegas its almost as if its an expansion except with a full game price tag. You essentially have a very similar environment, smaller map, and it the choice system that was so good in FO3 has gone down in value. What i mean by this is that in New Vegas you very rarely have to make some big decision that will affect the game in a huge way except when dealing with factions. I have played through the game a couple times and basically it seems like i choose a faction and i just do quest for that faction while either killing/ignoring the rest of the factions. Take the NCR side quest for example. How many of those quest actually require you to make a decision? Very few in my opinion. In Fallout 3 right out of the game you had a choice of blowing up an entire city with a nuclear bomb. I mean that's a very important quest with a very important decision associated with it, and its just a side quest. So far in my play through i have rarely encountered quest that require me to make such a decision or even provoke any feelings with the decision i make.
Examples:
Sure you have to decided to eradicate an entire BoS branch. But seeing as how they stay secluded to one bunker and you really dont interact with them through the entire game till close to the end of the main quest line makes it seem pointless.
Same with the boomers and the rest of those ending faction allies quest. You really dont interact with them unless its in the main story.
This is just a opinion and most importantly a theory, it is subject to change and does not directly represent the Gaming community. Enjoyment level of the game will vary from player to player.