New Vegas has far more quests than Fallout 3, marked quests, unmarked quests and companion quests. There are far more options in how to do those quests. There are four main ways to finish the game. You can join or help pretty much every faction in the game, which you can't do in Fallout 3.
Funny how you say New Vegas can get "lonely" cause wasn't that the point of Fallout 3 "Lone Wanderer?"
The differences in Fallout 3 do take alot away from Fallout 3. It is why people are so critical of it.
Don't get me wrong, I enjoy Fallout 3 for what it is, I just don't think its a very good Fallout game. I rank it 5th out of the 5 canon games.
I do need to get my hands on the first two games. Would love to try them.
Theres more quests in New Vegas? I didn't know that. Feels like the FO3 quests are a bit more lengthy though, and sometimes NV can be a little talk/dialogue heavy. But I understand that its the type of game that it is, it is an RPG afterall.
And what I was saying about the lonley comment, it wasn't about companions really, just more towns or settlements, friendlies, and enemies. Just seems to be a huge gap(of empty) in the map at times with NV, compared to FO3.
That being said, I love what they did with NV. I love the settings, hardcoe mode, and how they made the normal mode much more difficult then FO3. There is no 'god' mode in NV, and thats really cool.