** spoiler alert ** 
 I realize that I am in the minority of opinions here, but I think this is my least favorite in the series so far. 
 (Hey, put down the pitchfork, I still LIKED it, just not as much as the first four; chillax). 
 While the plot itself is interesting enough, and we do get some important character development, I didn't care much for the pacing. It was the first of these books that felt dragged somewhat to me. We got less urban folklore whimsy in this one and more wizard kids practicing waving their sticks around. Now between bouts of stick waving, a lot of key elements of plot do happen/get resolved. Ron and Hermione continue to expand as characters in general; Voldemort continues his hidden rise to power begun at the end of the last book; Harry realizes he doesn't like Cho as much as he thought he did; Sirius dies, etc... 
 There were fun elements but the morbid tone of the -- at times plodding -- plot just felt a little too heavy handed. I just got sick of all the "unfortunate twists of fate" and emo!Harry moments by the time I'd reached the end of this book. I'm not saying they weren't important to the storyline, or that Harry didn't have good REASON to be angst-filled, or even that it was too melodramatic, just that I personally felt that over 800 pages of it was too much for me. 
 Also Umbridge annoys the heck out of me. I know she gets her just desserts in the end but just reading -- hundreds of pages! -- about her makes me want to slam the book shut half the time. 
 The two characters I really DID enjoy in this book were Luna and Ginny. Contrary to Ron and Hermione whose character growth we are CURRENTLY seeing in this book, the focus moments for Ginny seem to me to be how much she's ALREADY grown, and it's wonderfully done. I especially liked the scene where she tells Harry off for not wanting to talk to her about Voldemort when she knows better than anyone what being possessed by him is like. 
 The introduction of Luna was a GRAND idea for this book. The series desperately needed Harry and his crew to have closer friendships with people of other Houses. It's just become so much of the Gryffindor show by this point having a Ravenclaw join their group without being a romantic interest of anyone within it was refreshing. Also Luna herself is just a lovely character; she's funny, she's quirky, and you can tell she has a lot more common sense than the people in this book-verse give her credit for! 
 Reasonably recommended, if you're keen on following the whole series. Not a bad book by any stretch. 
 Looking forward to next book sometime soon, about which I have heard good things and hope I enjoy a bit more than I did this one.