Harry Potter spoilers ahead. Click the lj-cut at your own risk. I just finished the book and will discuss my overall feelings and views on it.
I feel completely vindicated when it comes to my favorite character. Snape did everything out of his unrequited love for Lily. He's the best character J.K.R. dreamed up and I think the books would be sorely lacking without his presence.
Other things I loved about this last book:
Gripping page-turning action
Tear jerking deaths of some great characters
Kick ass brilliant Hermione
Kick ass Molly Weasley
Albus Dumbledore's humanity over his deification
Neville being uber cool
The obvious morality tale and research that I know J.K.R. put into this shows, it really does.
The Lovegoods
I enjoyed everything involving the whole Gringott's break in and escape.
Things I didn't like so much:
Less humorous
Tear jerking deaths of some great characters
Ron reverting to form (even though he comes back)
The fairy-tale marriages (wouldn't happen IRL)
The epilogue (While I don't despise it, it really could have been a lot better.)
How easily Voldemort actually took over.
The weird explain it all scene in the King's Cross station in Harry's mind. (It was too forced.)
Anyway, don't know if it will ever happen, but I already have a great idea for a fanfic. Knowing my track record with fanfic though, I will probably never get around to doing it. Ah well! Great series. ;D