I have to say this is probably my favourite, too. (Must be because the Harry Potter series are the only books that can reawake that all consuming passion for reading that makes you read for hours and hours straight! And this was that in its best form, I basically read 12 hours straight slept a bit and then read the last 50 pages.)

On the one downside (and also I thought this about The Order of the Phoenix, with all these decrees of Umbridge's) I think its so political in a way that a german feels its almost taken fact for fact from Nazi-Germany, encoded and written down.
Muggle-borns having to register, being interrogated, fleeing the country - people listening to a radio station that reports the truth as germans illegally listened to the BBC...
I suppose it might be a little bit like any tyranny, but germans are sesitive . And i'm not necessarily saying its bad to do it like that, I just find it distracting sometimes.

Same with relying on other sources - the locket-horecrux? With burning itself into the chest and making the bearer moody and bad-tempered and actually make him think his worst suspicions are reality - how is that not just like Lord of the Rings? (It has to be destroyed, too lol)

But I'm just nit-picky because I utterly loved it! Rowling has that amazing ability to make a book both incredibly exciting and absolutely hilarious at the same time. Sometimes literally at the same time.

Hated the deaths though! Fred? That's like George, too. What will he do without his twin? And Remus, my favourite teacher and object of lust ... and Tonks, leaving their baby without parents... hmpf.
Even Snape... I mean, it would have been nice (sentimental but nice) to see how they would get along after Harry had seen these Memories...
Buts worst: Dobby! How could she kill Dobby? *pouts*

And I didn't mind the ending, in fact I really liked it (mainly because I was so afraid she's kill Harry! I mean atually kill him so that he is actually dead) - and because just the day before I got it I told someone in a discussion that that's exactly what I wanted - Harry marrying Ginny and have lots of cute babies. So I can't complain.
Besides - this ending will inspire scores and leagues of fans to write terrible fanfiction again. So for them it was rather kind of Rowling that she didn't reveal too much. Gets the creative juices flowing

I think the ending had to be sentimental, and even though the question I want to have answered most is also who Draco would have married and what all their jobs were, I like the mystery, too.
Besides it had my favourite line in the whole book: "Mum, I can't give a professor love!"