I played in a game like this a few years back (under slightly modified oWoD rules). It was great fun and if you can stand the wonky WoD dice mechanics, I'd recommend it. I've thought of trying something like this out from time to time myself. I have no experience with Exalted or nWoD (beyond reading through the core book and M:tAw) but have run and played all of the oWoD stuff. You might find the nWoD rules to be a tighter option and easier to get hold of. I'd also keep the following things in mind:
It is pretty easy for WoD characters to reach 5 dots in any skill and not much harder to get attributes up to a high level - far easier than it is to boost your stats and BAB in D&D, for example. This means that characters will be more effective in combat sooner than their D&D counterparts. Not necessarily a bad thing, if that's what you're after. You can also ameliorate this by upping the xp costs of improving stats under the WoD system.
If you go all-out in combat, WoD characters can die far more easily than D&D characters (except for low-level D&D characters, who are much more frail). Some WoD games tend to discourage this kind of character mortality, so you could also take that approach, or you could give characters more health levels to reflect the feel of D&D combat.
As for magic, you have lots to choose from. The sphere magic system in Mage allows you to create pretty much any magical effect that you choose, but it is very powerful and doesn't progress in quite the same way as D&D magic. Overall, you are probably better off ditching D&D magic conventions and building a new set using WoD rules. If you give all characters a "mana" stat, you can lump the various supernaturals' powers together and represent them as different magical traditions. Vampiric disciplines could reflect one set of techniques (with blood replaced by your mana stat), druidic magic could be represented by werewolf gifts (replace gnosis or rage), wraith arcanoi could stand in for necromancy etc etc. Plus you have the path magic of sorcerers that you can use in place of sphere magic if the latter seems like too much of a headache.
Just some thoughts - make of them what you will
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