!!!!SPOILERS!!!!
You have been warned...
I read HBP and I must say I was disappointed. There were some very powerful scenes (more powerful than in any other HP book to date), but the plot itself was kind of boring. The powerful scenes were only powerful because of character development that has been happening throughout the entire series. This is possibly the first HP book that would not stand as a good read on its own. Seriously, what was the plot? Teenage romance awkwardness? Who cares! When I read Harry Potter, I want dragons and dementors and time-turners and centaurs and all that other escapist fantasy. There was almost nothing fantasy-ish that was new to this book. Off the top of my head, I can only think of inferi, which played an extremely minor role in the book, and horcruxes, which were more backstory than anything else. All the other fantasy elements had appeared in previous books. And there was no slow buildup to an exciting climax like in Order of the Pheonix. The climax was exciting (because of character development from previous books), but the climax was only 3 chapters after hundreds of pages of boring backstory. I didn't care at all about the titular plot line. So Snape called himself the Half-Blood Prince as a nickname, and wrote some helpful comments in one of Harry's textbooks? So what? Let's hope #7 is exciting, because Rowling sure took enough time setting up for it in this book.
Now that my rant is out of the way, I'd like to make some predictions about book 7. First, Harry Potter will NOT return to Hogwarts. I say this because Griffondore finally won the Quiddich Cup in book 6, and I think Rowling did this because she new Harry wouldn't be competing in the Quiddich Cup in book 7. Second, Wormtail will play a very importanct role in the defeat of Voldemort. I say this because, in book 3, Dumbledore told Harry that he would someday be glad that he had spared Wormtail's life. Wormtail is the anti-Snape, whose role will be to restore faith in the good of mankind and the power of love over darkness after the tragic betrayal at the end of #6. Snape was originally evil (he was in Slytherin), then for a while it looked like he was good, then we found out he really was evil all along. Wormtail was originally good (one of Prongs' best friends), then for a while it looked like he was evil, but in the end we'll find out he really is good. Maybe his role will be to kill Snape. That would be perfectly fitting.
Someone mentioned a mirror given to Harry by Sirius. I don't remember this, but if there was a mirror given to Harry, perhaps it is a horcrux? Maybe the mirror was owned by Ravenclaw? Then perhaps Sirius knew about the horcruxes, and maybe the B in R.A.B. stands for Black. Or maybe, if R.A.B. knew Voldemort personally, the B stands for Borgin? Or Bottes? This is just speculation...R.A.B. could be some completely new character. But I'm confident that Harry will not return to Hogwarts, and Wormtail will turn good.