I liked it. but, I love the series, I don't think I could ever dislike it. I've read the books so many times, that I think I have too much emotional involvement in the characters, particularly Dumbledore. I admired the way the character was written, especially because I really felt his devotion to Harry. I didn't feel that way about S. Black. I was indifferent to his passing.
However I feel the book was predictable. At least, to me. I think there was a lot of foreshadowing that made the death of Dumbledore too obvious, but near the middle of the book I stopped and thought who would be killed off out of all the characters - who means most to Harry and what would hurt the most? Dumbledore is the clear answer - as he has been Harry's guide/protector throughout the series. He was giving Harry all the information he'd need by going through memories in the Pensieve so Harry could go it alone in the final book. I kept hoping though, that Dumbledore wouldn't die, since he was such a powerful wizard, and I found him to be entertaining and often a source of humor in the book.
The betrayal: I always though Snape was a bastard of course, and it sucks that Dumbledore put so much trust in him KNOWING he was such an accomplished Occlumens. I was hoping for some reason as to why Dumbledore trusted him so much, but nope. I guess that info died with good ol Albus.
I think Ron and Hermione suck as a couple. I often think Ron sucks as a character, but I'm not really that fond of insensitive teenage boys so perhaps that is why.

I think Harry and Hermione would be better suited.
As for Malfoy, eh, they gave him some more depth but he's still just as much of a fuck as Snape. I hope they both get what they deserve.
I liked the Tonks/Lupin angle. I think Lupin needs some lovin.
I know some of the reviews have criticized the book for not being very action packed in the start and while I agree - all the books have been like that, for the most part. The last book had more drama going on because Umbridge was there and causing so much controversy. I wanted to throw that book and I got up so many times in frustration because it was just so much of an injustice the way the Ministry was acting, and also because Harry was acting like such a prat.

CAPS LOCK OVERLOAD, for sure.
I was really pleased to see Harry and Dumbledore together so much. He deserved some positivity after all he went through in the previous books, things were finally going his way, as opposed to Order of the Phoenix where it was all downhill. I enjoyed the backstory and depth and I definitely agree it set a solid foundation for the last book.
Final criticism: I did not like how it would just comment on who died or who disappeared. I wanted some more story on that.
I predict Harry will die in the fight to kill Voldemort. JK Rowling doesn't seem to mind killing off prominent characters!!