Oh my God. If you put me in a land of fiction then it takes a lot to make me cry or even tear up (for example not a thing when Dobby died in HP) but the last third of Mockingjay almost had me actually crying, not at the particularly violent bits but how Katniss and Peeta where not good with each other, it was actually heart wrenching. And when Katniss was thinking about Prim at the end, that bit got me to.
I suppose you could say that its a happy ending, but at the same time it really isn't, bitter sweet is the term I suppose, there's not many people left at the end that were there in the beginning and the one's that are left are shown in a totally different light (i.e. Gale, though I wasn't his biggest fan in the first place, contraversial I know) and Peeta for that matter, though that wasn't exactly his fault. Though the ending, especially by dystopian standards is extremely happy (see previous reviews on 1984 and The Handmaid's Tale).
There was far more character development in this book and it really paid off on Collins' writing style, and as I said above you not only see characters in a different way but in a shocking way for some of them, even Katniss and I was inside her brain! I was particularly shocked by her vote in the end, I thought she would be against that. But the thing about Katniss was that it was clear she really loved Peeta, she really cared about getting him back to her, and whether she realised it or not that was in a romantic way as well as a you're-my-friend way,
Again I seem to have read this book, like The Hunger Games and Catching Fire, in a ridicolously short amount of time, especially considering I spent several hours plotting with my housemates on how to get our back door key back from our neighbours (we were successful) and I think, though part of that is to do with the books being very short compared to what I am used to and far less complex (i.e. Game of Thrones) but also because they are riveting, you are always wondering what will happen next, and whether or not Katniss will realise she loves Peeta, and whether they get to share their love and have a happy rest of life (something I won't tell!). Collins has created rich characters who just want to make you keep reading on!