I would like to ask, what part dissapointed you in the 5th book.
The part that i really didnt like was the Giant part when Hagrid came back, it was horrible i though. All this time he was gone, i thought it would add a BIG thing to the story, but it was only Gwamp that was added, scaring the centaures...it was quite dissapointing.
ETA: Be sure to make sure there are not other topics already in existence for this topic. There is a book 5 comments and criticisms thread:
http://www.broomsticksandowls.com/forum/viewtopic.php?t=1219
this post will fit nicely into. I am closing this thread...but, just so you know, I am not picking on you!