Ok I just finished the book and I must admit I liked it - though book IV is still my favorite.
My most favorite character in V: McGonagall (love it how she treats Umbridge)
My least favorite character in V: Dumbledore (where was he when Harry needed him?)
Btw, at Salon.com
in David Harris' blog you find a summery of each chapter. David has some other interesting things to say about Potter here