My thoughts on the sets:
Oh, SPOILER WARNING (though if you're looking at the set pics and reading this thread you already have probably read the book).
Draco and Buckbeak: That Buckbeak is really cool. Unfortunately it's the only thing in this set, except maybe the new pattern book, that I really want--I've already got several Dracos (albeit yellow, but I'm not overly thrilled by the peach), and the few other pieces are common. So the question for me is will I be able to Bricklink Buckbeak for less than $6.00? If so I'll just do that instead of getting the set.
Marauder's Map: This is my least favorite. Aside from the minifig statue (ghost?) it's all common pieces. The use of the potions scroll instead of a new printed tile for the map is a disappointment (or is this not the final product?).
Lupin's Class: If you've got Hogwarts and some of the other Hogwarts sets (e.g. Snape's Class), this is a great addition. Presumably there is a wolfman fig behind the rotating panel so you can make Lupin change. I'll definitely get one of these.
Sirius' Escape: Lame lame lame. If those are truly new macaroni pieces that is cool, but I'm sure they'll start showing up in other sets, so that doesn't tip the balance for me on this set. Why is there no Dementor? That would make this set more buyable. I'll Bricklink a Sirius rather than buy this set.
Knight Bus: Very cool. I love all that purple. Also Padfoot.
Hogwarts Express: I don't mind rereleases, but I find it offensive that they seem to have put a Dementor only in this one set to get people to buy it, especially when you'd really want to have several Dementors and one Harry, rather than a huge pile of Harrys and one Dementor unless you want to shell out lots of cash.
Shriek Shack: Good design, lots of good pieces for Castle or Town builders. I wonder if there are more figs (e.g. Peter Pettigrew human form). What's the construction at the bottom for?
Hagrid's Hut: A good set, but I prefer the first version, even with the fake roof. I do like that this set seems to close up into a complete building with four sides. I'm a little confused as to the reason for the seemingly random color scheme, but this set will have many parts for Castle or Town builders, especially if you wait for a sale.
Overall, a couple of losers, a couple of real winners, and a few in the middle. The only thing that really bothers me is the thing about the Dementors.