There has to be a conclusion. Usually a tough exercise, and all the more so considering the anticipation for this book. And let me say it clear: JK Rowling blew it. I hadn't really been thrilled with the previous books (with plot elements not being fully exploited and major revelations ending up disappointing), but as this book leaves aside the usual "boarding school year" structure, the author's limitations come in full view.
JK Rowling might have the whole universe in her head, she struggles when it comes to conveying the sense of passing time and laying out geography. Scenes follow scenes, and without Hogswarth to tie everything together, there is no sense of cohesiveness there.
Worse, character evolution is close to non-existent and borders on caricature in this last episode -- Harry, Ron and Hermione bicker and fight, as they've been bickering and fighting for six books now, resulting in the same counter-productive effects as before, and one would wish they'd know better by now.
As for the big finale, things get resolved mostly through happy coincidence, while a lot of the big things hinted at in the previous book are solved in a matter of pages. The ending proves another thing: that JK Rowling is caring too much for her characters to bring a satisfying and dramatic conclusion. The epilogue (a pure overdose of sugar in itself) adds another touch of bad taste to what was a huge (if somewhat expected) disappointment.