I've written down some of my thoughts. They're long and rambling and not read though so probably full of typos and bits that don't make sense, but whatever:
First of all, let's look at the theories that did or didn't pan out. Be warned, this may just be a self-indulgent opportunity for me to bask in my rightness:
Harry Potter lived. I knew it. I should have made a bet or something.
Snape was a good guy all along in the books and he died. I was right about that too, although he didn't die in as heroic a fashion as I thought he would.
Petunia. I've always had this theory that Petunia had wanted to be a witch too and only decided Lily was a freak after she found out she wasn't. I was kinda right. She was a bit more scornful of Lily and Snape than I'd expected before she got her rejection.
One Big Happy Weasley Family. Another thing I was sure about. Although in my version, which preceded Half-Blood Prince and the canonisation of Harry/Ginny, Harry was a member of the family in his own right. He didn't need to marry into it.
Snape and Lily. I've seen the idea that Snape was in love with Lily around for a while, although I never actually subscribed to it myself. I bet there are a lot of people feeling smug though, because I also remember others ridiculing the idea.
Harry is a Horcrux. When I finished the last book I immediately thought this, then I kept wavering back and forth on the idea because I wasn't sure if it was actually possible. Turns out it was.
Sirius. I was completely wrong about this one. He really did just fall from a curtain and die. How... sucky.
And now, issues that I have with this book:
At the beginning the Death Eaters say the Order won't transport Harry by Apparation because they mistrust the Ministry, yet they all Apparate later with no qualms. The Death Eaters also say that they'll know if he Apparates but how will that help them? Later in the book it's explicitly stated that Apparation can't be tracked so all they'll know is that Harry has left Privet Drive, they won't have any idea where he is.
Harry has special protection because his mother died for him and at the end he gives protection to the others by being willing to die for them. Does this mean that no one else has ever tried to protect a loved one by sacrificing their life for them? I mean, if protection is that easy to give surely loads of people have it.
If Grindewald had the Elder Wand, wouldn't he have used it when duelling Dumbledore and therefore won?
Harry says that if he dies a natural death then the Elder Wand will lose its power because no one has defeated its master. Yet he just made a big deal about how he defeated Draco by taking Draco's normal wand, after Draco defeated Dumbledore by taking his. So all someone has to do is take Harry's wand and they're the new master.
If Harry can't be killed because Lily's protection still exists in Voldemort, does this mean that he has been impervious to death since the end of Goblet of Fire? I'd have thought a bigger deal would have been made of this.
Why did Dumbledore have the Invisibility Cloak for so long? Did it really take months for him to examine it?
She wasn't exactly subtle with the Nazi comparisons, was she? A European wizard who believed some people were inferior because of their birth and built a prison to hold his enemies with a quote over the entrance? And, just in case that wasn't clear enough, he was defeated in 1945. Then all that stuff with the muggle-born register and propaganda leaflets.
I really liked the way the book followed the main trio for almost all of it and took us along for the ride. We only knew as much as they knew about what was happening in the outside world, it was like we were going through it with them. I like that a lot better than knowing everything and waiting for the characters to find out.
I see the moral message was alive and well during the fight in the Room of Requirement. Crabbe was the only one who tried to kill anyone and the only one who died.
Naming your children after both your parents is just creepy. I mean, come on! There was Lily and James Potter the married couple and now Lily and James Potter the siblings. That's got to screw with you. Even more so than being named Albus Severus.
Also, Hugo? WTF?
Hedwig - Nooo! How could you, JK? How could you!
Mad-Eye Moody - Eh. I never liked him as a character anyway. He always bored me so I was quite pleased to see him snuff it.
Wormtail - Good riddance.
Dobby - Ah, Dobby. You were so irritating I think most of us wanted to kill you ourselves, but it was still kinda sad when you went.
Fred - Well, I said a Weasley would die. I really wish we'd seen more about how this affected the rest of the family though. Especially George, since the two of them have been more like two halves of a single entity than individuals. How will he cope by himself? I think I may have been in the right area with my madness and suicide theory to be honest.
Remus and Tonks - I think she just did this to give a parallel between Harry and Teddy Lupin. And because they were well-liked characters. They just got married and had a child, which of course ups the tragedy factor. But still, they were always kinda expendable, it just depended on whether she would do it or not. And she did.
Lavender - Did she or didn't she? She was twitching when we last saw her, but obviously she wasn't important enough to give us a definitive answer on her fate.
Colin - Eh.
Snape - I was certain he was going to die and he did. There was no way he could survive to the end. I really liked how we got to see his backstory though, his motivation and his actions throughout all this.
The Epilogue. I liked it. Yeah, it was a bit fanficcy but that's not necessarily a bad thing. It's a neat ending to the series and wraps us the characters' journey nicely while showing that their lives continue.