I'm going against the grain here and saying that yes, you get Adept Powers along with your Magic.
The rule in question is simple: Adepts get an amount of Power Points equal to Magic. Essence drain increases their (actual) Magic. Therefore it gives Power Points. There is no restriction anywhere on "temporary" Magic, or the magic from Essence Drain, not giving PP.
It being OP doesn't hold up in my opinion. Magician vampires get the full benefit from boosting Magic this way, and arguably magicians have more of a use for Magic boosts than Adepts do. Why would Adepts get the short end of the stick here? If you don't want to deal with players eating people to make them more powerful, don't allow infected characters - it's kind of their shtick.
Bookkeeping isn't really a big deal either. Yes, you have to keep track of what powers you have, but you know and accept that if you make a vampire adept. Plus, only the player has to do that - and it's not that much work, since you'll likely know what you want anyway and PP's don't tend to be overly complicated.
Besides, it's not going to change that much; it's not like a vampire will fluctuate wildly up and down over the course of a session. In fact, in-session adjustments down will practically never happen, and in-session adjustments up will probably happen once in a session, and then not every session.
So, since rule-wise you would, and there's no good practical reason not to, you get PP when your Magic increases.
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That said, I do like Sendaz's system, and I'd be tempted to impose that as a houserule. As a player, that's probably how I'd play it anyway.
