A) Hi Bonnie! Love to MJ.
B) Obviously, I am biased towards the series... hence my username. ;p
As for the fifth HP book, it had been my favorite. The overall plot was more insidious and psychological than the previous installments, and the new characters were a hoot, especially Luna.
C) I was quite upset that people were shouting out the spoilers at book stores after reading HBP. I tried to avoid spoilers online and such. I had a few theories that were proven to be correct, and there were a few big surprises as well. Since I enjoy writing fanfiction, I was prepared for many alternate possibilities. I'm hoping that the final book ties things up neatly enough, especially questions that I had that were not answered in Half-Blood Prince.
(And I'm still rooting for Luna/Harry romance, but will enjoy Ginny/Harry if written in a believable manner.)