I've heard that a fair few people found the ending of Mockingjay rather disappointing, at least compared to the other two endings. I actually really really liked it...possibly for the same reasons some of my friends didn't like it. I did find it unsatisfactory with Katniss being unconscious for the big final battle and not seeing the actual end of the war, but I actually liked the unsatisfactory nature of that. Katniss is never a proper soldier in the war, like with all the other books she is pretty much just a tool being used by other people to serve a purpose. She gets very little say in anything that happens to her, despite having the most right to do so (it being happening to her and all). Therefore her not being able to storm the mansion and shoot Snow in the head after all this effort she's put in due to the actions of others fits in quite nicely with the rest of the books.
If Collins was trying to make out that everything would be all nice and shiny once the Capitol had fallen then I think it would have made sense for Katniss to see the end of the war, even been instrumental in it, but since it's quite clear that there is still a lot of work to do, and a lot of people are still painfully fucked up by what's happened to them, continuing the theme of the main character just being an unwitting tool in other people's plans was perfect. And I liked that not everything was magically okay once the war was over. That Katniss and the other Victors were still damaged beyond belief (the screaming nightmares, Haymitch coming up with a knife if ever woken unexpectedly, that Katniss still doesn't truly believe she's safe even twenty odd years after everything is over) made it all seem very realistic. Katniss was always an incredibly strong character, but she had such horrific things happening to her (even if she handled the first games very well, they were a very traumatic event even without the rest of the shit she goes through) that recovery was always going to be difficult. Watching her steadily unravelling was great! I really liked how Collins didn't pull any punches and just piled more and more crap on the poor girl. Because hey, this is a crappy crappy situation and it's not going to get better while people who think the Hunger Games is an okay punishment are in charge (looking at both presidents here).
And the last line of the book..."There are worse games to play". Ouch. Right in the feelings.
And one last rambling set of thoughts...the love triangle. Possibly because I entered the books knowing that she was going to end up with Peeta coloured my perceptions of this, but it never struck me as a particularly strong triangle. Terribly sorry Gale but it was always going to be Peeta. If Katniss hadn't been picked for the Hunger Games then you'd probably have ended up together and had a very nice life. But since she was...yeah. There always seemed to be something setting the Victors apart from everyone else they met because they were the only people who really understood what it was like. Gale might have been able to keep Katniss calm during her nightmares and enabled her to sleep, but he wouldn't have really understood them because he hadn't been in the games and so didn't know what it was like, exactly what she was seeing.
I had to stop part way through this to go hang out on a beach so the flow of my thoughts got a little scrambled, but I think that's the jist of it all. Aside from the bleak ending and Katniss's grief over the loss of her sister almost making me cry. The Hunger Games was the only film I've ever cried at and came close to being the only book too. It does seem to just hit me right in the feelings. Bastard book.