Ok, before I start a few warnings. This will contain spoilers (though since I'm writing this a year after the release I don't think it's too much of a tragedy), it will be long and it will be negative because I really didn't like this book.
Reading books one to five I was very impressed with the storytelling from a novice novellist. There was magic, there were characters you could love, and sure there were some cliche'd storylines, but they were interspersed with really interesting sidestories (Peeves, SPEW, Weasley's Wizard Wheezes). I was enthralled as a teenager and I am enthralled now as an adult when I re-read them.
But I have to say the the quality dropped markedly in books six and seven. The ramblings (that started out cute in GoF and OotP) have become pronounced and boring. The characters have lost much of what made them endearing, and the plot has gone to hell.
Focusing on Deathly Hallows, I had a very strong feeling that six months before her deadline, JKR went on to the internet, discovered that everyone had guessed her 'twists' (honestly, who didn't know that Harry was an accidental Horcrux, RAB was Sirius's brother, the diadem was at Hogwarts, the locket was at Grimmauld Place, Dumbledore ordered Snape to kill him, Snape was in love with Lily and Ron would be a it and abandon Harry and Hermione?), and felt the need to come up with a new plot device. This would explain the incredible stupidity that is the deathly hallows and the plot holes and gaps in logic that involve them.
Now, it has been a while since I read it so some of my names and such might be wrong, and if it does answer the questions in the book in such a round about way I apologise, but the Elder Wand does not make sense. I'm willing to accept that it follows it's own set of rules separate from those of other wands (where Haary can use Hermione's wand almost as well as his own and all of the disarming they did in book five didn't make their wands all change ownerships) but the course of events whereby Harry became the owner of the wand are just plain silly. If Grindelwald simply stole the wand from Gregorovich (sp?), how did that make him the wands owner? If the wand is unbeatable, how did Dumbledore defeat Grindelwald (I know Rita Skeeter theorised that Grindelwald surrended, but how does that pass the wand's ownership to Dumbledore. Surrender is not the same as defeat). And if the wand is unbeatable, why was Dumbledore unable to defeat Voldemort when they dueled on OotP? And also, is Harry really so conceited and stupid to think that no one would ever defeat or disarm him, making them the owner of the wand? Shouldn't he have broken it? If he does become an auror in later life someone is bound to disarm him eventually, and if they knew about the wand, they could easily steal it back from Dumbledore's tomb.
The other major thing that ticked me off was the characterisation. Hermione, Harry and Ron have always been some of my favourite characters, but here they are acting completely different from previous books. Harry using Unforgivable curses without a hint of remorse, and not comforting Hermione when Ron takes off, instead staring at a 'Ginny-dot'. Can we say creepy and stalkerish?
And Hermione, who for the most part was still loyal and brave and smart (loved the bottomless bag bit, and her being there for Harry at Godric's Hollow), was so pathetic when it came to Ron. I know love makes people do the wacky, but crying for days on end when they're supposed to be searching for Horcruxes, kissing him in the middle of the war because he finally showed a tiny inkling of care towards the house-elves.
And Ron. Gah! I mean, I love Ron, but you would have thought he could have grown up a little, just a smidgen. But no, running away because of the locket (one ring to rule them all...). Those who defend him saying it affected him more than Harry or Hermione because he had more insecurities is just dumb. Harry and Hermione had just as much to be insecure about. Harry, with his saving-people-thing, could easily have gone nuts with the locket around his neck and ran away from the others because he was terrified that they'd get killed. And Hermione has always been insecure, about being Muggle-born, about proving herself, about Ron and Harry and their friendships. Sure, he wanted to come back the moment he left, but he still left. Which I could accept were it not for such a stupid reason. And then he got his 'super-moment' which was so lame. Honestly, 'Ron can remember and copy paseltongue', uhuh. Wouldn't it have made much more sense to say, have Ginny come along, who could possibly still say the word from when she opened it under Tom's control in CoS. And then Ron mentioned the house-elves, to make himself 'worthy' (JKR's words, not mine) of Hermione. For one thing, why does he need to make himself 'worthy' since she already loved him for all his insensitivity and insecurity, and why did that 'worthiness' have to be something that Harry already had in abounds?
Yes, I am a H/Hr shipper, but that is by no means the reason I hated this book (as you can see from above). If H/Hr had been handled as badly as R/Hr or H/G, I would have hated it. But the fact remains that the most romantic scenes in this book were between Harry and Hermione. At Grimmauld Place when Harry showed Hermione the picture, at the wedding where Hermione beamed at Harry, at Godric's Hollow where they strolled arm in arm under the kissing gate in the snow. While in canon, Harry married Ginny and Ron married Hermione, that will never convince me that they are the better couples. Harry and Hermione had the friendship, the trust, the alchemy. They were the most developed relationship in the series, and the fact that they didn't end up together in the book doesn't change that.
The final things I feel like picking on - the epilogue came across as being written by a teenage fangirl. No depth, no meaning, just stupid-named kids. I get that JKR wanted Harry to end the book with the normal family life he never had, it could have been handled so much better. And seriously, Albus Severus? That poor kid must have been teased horribly. And why Severus? Sure, he turned out to be not evil, but for Harry to chance his mind about the man after seven years of abuse and ill treatment just because he was scamming on Lily. It's just gross. And unrealistic. I was so hoping there was more to Snape's story than twenty years of unrequited love. Gah. It may have been a sweet way for him to become not evil, but Lily was very, very dead for a very long time, and no one holds on that hard to love. If caring for her wasn't enough for him to stray away from the dark arts while she was alive, why was it enough when she was dead?
Also, the invisibility cloak was supposed to be infallible, and yet Moody saw through it in OotP and Dementor's could see through it in PoA, supposedly. And, my god did the death scene's suck in this book. Yes, its a war so plenty of people, including main characters were going to die, but when I felt worse about Dobby than I did about Remus (who is one of my favourite characters) you just know that the author hasn't put enough emotion into it. He was the last of the Marauders, for god's sake, he deserved an on-page death at the very least. Maybe defending Harry or Tonks. Something!
Well, there ends the rant. There were a few good points in the novel (like Godric's Hollow, before the stupidity of Harry not realising that Bathilda was Nagini, and the awesomeness of Neville) but they were few and far between and do not at all make up for the rest of the drivel.
Read it because it is the conclusion to a series that took seventeen years to write, but do not expect the fireworks that such a finale could have been. There's better fanfics out there.