Yeah, the only thing 3rd person is good for is for something interesting to look at while travelling and perhaps judging the odd jump. Combat is difficult at best while looting is impossible. Indeed, just walking around indoors in 3rd person is really awkward.
From all accounts New Vegas uses the exact same engine as FO3 with little if any modifications. Most of what they've changed has more to do with stats than the nuts and bolts of the gameplay. Part of why I'm not too enthused with it. I'd rather wait until this one is in the bargain bin or steam sale since (as good as FO3 was) I rather hoped they'd taken the time to fix that stiff clunkyness that it had inherited from Oblivion. Not just the animation but there was something weird about how the guns fired, especially the automatic weapons. Like a delay before firing and an irregular firing pattern that always sounded too...slow? Oh and I never got the hang of melee combat, so you can imagine how well I'm getting on with Oblivion!