There's a restaurant in my neighborhood where we can go to get a vegan soy burger fixed up on a bun with all the trimmings, plus a big pile of french fries. Now, I love french fries (who doesn't?). But obviously, they're not something I can eat all the time, or even that frequently. And the indulgent delightfulness of eating french fries would be lessened, in fact, if I ate them all the time.
The Covenant is like that pile of salty, fried potatoes. You love it, partly because you know it's not healthy or righteous or defensible, and because it tastes so damn good.
Take the classic Lost Boys, add in one of those "decadent rich teenager" films like Cruel Intentions and stir well. Mix in a little bit of The Craft, a dash of Swimfan, lightly season with both straight and gay soft p*rn, and you get something like this movie. I mean, it's got everything: hot naked rich boy-athletes at prep school who drive fast cars and oh, yeah, happen to be witches; cute girls in the showers (maybe being stalked...); the classic have and have-nots school movie conflict, the creepy half-undead guy; drunken rich mom; sexy scenes of library research! in old moldering books; and oh-so-beautiful scenery. Ya gotta love it. (and there's plenty of teasers for a sequel. In fact, there was probably a whole plot thread that could/should have been amplified (maybe in the director's cut?) because I kept waiting for the smart-but-poor heroine to start, you know, kicking some bad-witch-boy ass. Maybe in Part II.)