I wouldn't let the intro to NV put you off:
Like the intro to Fallout 3, it's intended to show somebody who knows nothing at all about the game enough that they can at least get themselves killed competently, rather than because they can't find the stimpack in their inventory and don't know what VATS is. If memory serves, it's also a fair bit shorter than the Fallout 3 intro(which was well done, and so fine the first time; but having to spend ten minutes being a baby and another 15 dealing with adolescent vault-bullying every time you want to try a new character build gets kind of dull). The character creation stuff in Doc Mitchell's house is obligatory; but you can skip Sunny Smiles' quest entirely(though it's a generous early-game source of caps and 5.56 rounds, so you might not want to).
Once you get past the intro, the game mechanics are largely the same(SPECIAL and VATS); but there is some additional polish to the skills and perks; the gameworld is really markedly different from the Capitol Wasteland; the local factions and characters are mostly well done and don't overlap at all with FO3(the Brotherhood of Steel is technically present in both games; but in very different capacities).
NV isn't a wildly radical re-imagining of what Fallout should look like in 3D or anything; but it's modestly more technically competent and polished than FO3 is(hence the existence of the Tale of Two Wastelands
project; and it is very much it's own RPG. FO3 is a much more 'apocalyptic' take, since Washington was an obvious candidate for getting nuked to hell, and there's a lot more crumbling-cityscape and deaths by radiation and supermutant attack; along with the fact that the East Coast Enclave are still a reasonably viable force. NV is very much post apocalyptic; but there's a lot less tightly packed death zone and a lot more wilderness(some of it largely benign, some brutally lethal; seriously, don't fuck with Cazarores, or try to stop a deathclaw with anything
.308 AP) and political and military struggle between new powers that aren't just scrabbling for canned goods in the smoking rubble and are actually starting to jockey for power in a post apocalyptic rebuilding.
You obviously don't have to trust my advice or anything; but especially if you already own the game(or find it when it goes on sale, which it frequently does), you are really missing out by not giving it a few more minutes to make its case. Let the doc patch you up, don't even talk to Sunny if you don't feel like it. If you really hate the intended early game, you can even go 'in reverse' by heading directly from Goodsprings to Camp McCarran: it takes a touch of practice; but there's a fairly safe path from Yangtze Memorial(veer to your right a bit if you see radscorpions on your left, early game weapons don't do much against their armor) and between Sloan and Black Mountain more or less straight to Repconn HQ. There are deathclaws on your left and supermutants on your right; but even feeble sneak skill should allow you to avoid the attention of the deathclaws without getting too close to the supermutants(always err on the side of too close to the supermutants: a deathclaw can run faster than you can, and is functionally unstoppable at low levels. A supermutant is something you probably can't defeat at low level; but it will usually stand and shoot at you and not pursue particularly aggressively. Unless you get particularly unlucky, or your character build has nearly no HP, you can survive being fired on, for a short time and at a distance, by a supermutant, which gives you time to get away).
Once you make it to Repcon HQ, you can either swing right and head to freeside, or head to Camp McCarran(if you go this way, try to stick reasonably close to the wall, where NCR troopers will provide a mixture of fire support and meat shield against any fiends. You can usually score some energy weapons from the fiends and and some 5.56, a service rifle, and an NCR uniform from at least one luckless NCR trooper; this lets you take the monorail straight to the strip and gives you some stuff to sell).
If I sound biased, that's because I am; but it really is worth a look if you liked FO3.