Magic

I agree with you on the magic being inconsistent, but my larger problem with it was that became too simplistic. The earlier books were full of new and unusual magic. In the later books, magic use seemed to be limited to unforgivable curses, along with the occasional stunning or disarming spell. I was hooked by a story about a kid living at a boarding school teaching magic, and the last few books basically threw that away entirely, with hogwarts (as well as study in general) dwindling into the background. Ah well.

Dumbledore

I hated the way in which Dumbledore died. I didn't care too much about his actual death, but I spent the rest of the series waiting for his death to mean something, or to be explained. Neither one ever happened. Dumbledore going down without a fight, begging Snape to do it. . .both were so completely out of character that I knew it had to be a trick. But it wasn't. It was just a very puzzling, anticlimactic death. Cedric's death was far more meaningful and dramatic, and we only knew him for a book or two. Dumbledore was Harry's mentor for the entire series, as well as the most powerful wizard in the world, and he got nothin'. Bah.

The Epilogue

Everyone I've talked to hated this, but I actually enjoyed it. It was cheesy, true, but I really like to see things get back to normal after big battles for some reason. Too many stories show you the fight, but very little of what everyone is fighting for. Always seems like you win the prize, but never get to find out what it is. Sure it might make a more dramatic ending to fade to black as the last arrow falls, but, darn it, I want to know if my gang got their happy ending or not.