Well, it has been about a month now, and I think I have to say I enjoyed Fallout 3 more than New Vegas. The story and complexity is worlds better in NV, from Hardcore Mode to weapon mods, speech/barter challenges, ways to finish each quest that differ from the simple Good/Evil choices...but despite all that, what NV really suffers from is the Wasteland.
Aside from New Vegas itself and the two primary military bases (NCR and Nellis), there really isn't all that much to do. It seemed overwhelming my first time through, but I'm seeing more of it now. You go to a town like Novac and there are three sidequests, you go to the NCR Mojave Outpost are there are two. You start in Goodsprings and there is one. It really makes you appreciate having to go back to Moira in Megaton nine times to complete the Wasteland Survival Guide, or getting creepy stalker love letters sent from Mister Burke at the bar. They were small things, but it made Megaton still feel alive after you had moved on to the greater Capital Wasteland, not frozen in time like Goodsprings and Primm are.
It would be nice to have a reason to come back to these places once in a while besides dropping your loot off and going to the doctor.
But the biggest problem is that there is almost nothing to find in the Wasteland between these cities and towns. Ooo, I found another abandoned shack with a single stimpack and 12 9mm rounds. But this time there were molerats outside instead of Cazadors!
I found something new every time I randomly roamed the Wasteland in FO3. A few times I found entire new areas in the maze of sewers and metro stations. That has been happening to a limited extent in NV, but it isn't anywhere near as exciting. Despite the new freedom of finishing a quest 4 different ways, the game feels so more structured. There were dozens of unnamed quests in FO3 you pretty much wrote your own story for, in NV you find mostly bones and empty boxes.
The fact of the matter is there isn't really anything going on in the Mojave Wasteland. No huge battle between Supermutants and mercenaries, no lone Enclave guy taking potshots at radroaches, just the occasional NCR patrol getting ambushed by Nightstalkers and one disguised Legionnaire attacking some random guy.
Despite all the radscorpions and geckos that keep attacking me, the Mojave wasteland seems so...lifeless.
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And Boone is totally overpowered. He's so good the game isn't even fun. Cass is a bitch, I need how much speech or barter to get you up off your drunk mopey ass? That's despite you being critical to another quest line. Gannon is even worse, 75 speech!