I was there. I think that it felt like it has the original Fallouts in its atmosphere. I mean, Fallout 3 felt like I was playing Obsidian - quests were always about 20-30 minutes long, even if they seemed short, I knew what to expect, and there were no exceptions, as far as I remember. F:NV's writing and quest composition reminded me of the original Fallout games. I actually had a dialogue option which required me 6 IN. The combat is pretty much the same, from what I saw, though you aren't immortal in VATS anymore, and I saw a guy with a rifle with a little more DPS than the Grenade Machine Gun - he was attacked by a Deathclaw, he spend all his action points in VATS and did some additional headshots outside VATS, and the Deathclaw still had like 90% of its HP. I hope Super Mutants will be as hard too - I remember when I first encountered Super Mutants in Fallout 3, I thought "oh man, now there's no way to survive this" or something, and I was really surprised when I killed them with some earlygame weapons and low skills/level. Sadly, the world is still filled with millions of useless objects (though it seems like they aren't as many as in Fallout 3), stealing takes Karma and they use that old crappy Quick Travel system (no quick travel if you haven't visited the location). But the game really did feel more like the original ones, rather than Fallout 3 - in the way you feel the purpose of NPCs - you know like, when you see a NPC in Fallout 2, you feel what would be the dialogue with it in one way, and when you see a NPC in Fallout 3, you expect things otherwise. Fallout 3's NPCs were kind of "empty" and when they gave you quests, the quests always required much time. Fallout 2's NPCs were more open, with more personality in them, they were actually interesting. F:NV tend to be more like Fallout 2 in that manner.
I posted a thread in the F:NV forum section about some of my experience with the game.
There were three or four crafting platforms, I think - the ones for armor, weapons and ammunition used Repair; there was some sort of thing which used Science to craft meds. The ammunitions crafting platform used Lead, which is produced by smelting Scrap Metal. There were a huge number of new items.
Poison is something to consider now (first Fallout game with poison that actually does something!), though there are anti-poison items. Geckos sometimes drop Gecko Meat/Gecko Eggs/Gecko Hide. Hardcore mode has 3 additional bars: Food, Water and Sleep. Sometimes you have to eat things that aren't quite edible - for example, Gecko Meat has -1 strength. Stimpaks were much less useful (both in hardcore and normal) - or maybe that was because my Medicine skill was low.