Waiting for New Vegas

I still don't have a handle on how much New Vegas is going to feel like Fallout 3.  
I mean sure, it's going to use the same engine but I'm intrigued by the possibility of a lot of differences. For example, how much "dungeon crawling" could their be? Never been to Vegas, but I'm guessing it doesn't have an extensive subway system like FO3 made such good use of.  
This could seriously change the game, not just in the elimination of the long underground sections, but also in the way they were used to limit travel to parts of the DC interior at low level. 
Will this mean more of the New Vegas world will be open from the start? And how big will that world be? It's possible that areas of greater Nevada or even California are included. That would be pretty cool.  
I'm trying to avoid coverage, so it's possible some of these questions have already been answered. I'd rather imagine it till I get the game in my hands though.  
For me, FO3 felt like a real place more than most RPGs or open world games period. It will be very neat to see how New Vegas accomplishes that. 


Unhappy People

So in scanning the Fallout: New Vegas forums I was blown away by the rage directed at Fallout 3.  
If you think Fallout 3 sucks, do you like anything?  
Would nothing with the Fallout name please you except a pixel perfect port of Fallout 2, only with new missions?  
I just don't get this attitude.  
I love Fallout 2, I re-played it like a month ago. But that doesn't blind me to how awesome Fallout 3 is.  
I don't need to party like it's 1999 ALL the time.