I think the most important aspect to hit upon first is the characters/acting. I've been feeling very conflicted on this because the movie has changed some of my thoughts on the characters from when I read the book. But I'm going to break this down in some of the different characters. I suppose I should talk about Katniss first. Like I said above, I never liked Katniss. The movies have not changed that, and I'm not sorry to admit that. I certainly think Jennifer Lawrence is a great actress, but I've been wondering how much I've been enjoying her performance. In some ways, I was first thinking that this (and The Hunger Games) was one of her weaker performances on screen. But before you yell at me, let me explain. I saw Katniss to be very emotionless in the first half-ish part of the movie. I know a lot of you will argue with me about that, but that's how I saw it. Later on, I do think it got better, but there was still something that irked me. Jennifer Lawrence's performance didn't honestly help me at all. I still feel the same way about Katniss, and if anything, the movie reinforces how much I really don't like Katniss. I get why a lot of other people do like her, but I think the bad parts I see far outweigh the good that they see. And that's when I realized that maybe that made Jennifer Lawrence a good actress who has done a great job representing Katniss. What I mean is that for those who like/love Katniss, the movies have reinforced that, but for me, among the minority, it just reminds me of everything I don't like about Katniss. Lawrence's performance is good in that I guess she has done a great job playing who Katniss really is, for better or for worse.
Next, there's Josh Hutcherson and Liam Hemsworth. Let's start with Hemsworth first. I just...no. Sorry. Unlike many, I didn't mind Gale in the books (maybe because I never read past ~5 chapters of Mockingjay). But I don't think Hemsworth has captured the character's essence. Maybe part of it is the writing, but I think a large part of it is that he really seems unemotional, and that doesn't fit him, at least from how I interpreted Gale from the books. His performance has really made me dislike Gale. Who knows, maybe that's the point. Josh Hutcherson, on the other hand, I feel has done a great job. I don't even know why, but I was never fond of Peeta in the books, which is weird because in real life, I probably would like him. But I think Josh has done a great job of understanding and portraying Peeta, with a ton of emotions and expressions, and it's made me really like Peeta a whole lot more.
Haymitch and Effie are just as great in this movie, if not better (particularly Haymitch). Also, that mahogany reference? Perfect! Cinna is also still magnificent in this movie, and I'M SO SAD BECAUSE OF WHAT HAPPENS TO HIM LIKE WHY. (Just as a note, my favorites from the books were Haymitch, Cinna, Finnick, and possibly Johanna (I say possibly because I don't remember much from the books, so I don't know if I liked her).) Speaking of Finnick, MY GOSH SAM CLAFLIN. Yes, yes, yes, yes. He was so perfect as Finnick, and I just love him even more! And speaking of loving a character, Jo-freakin'-hanna! I fricking love that girl. Jena Malone, you are my favorite (not really but okay, maybe in this movie yes). Johanna was so beyond fantastic. I loved how snarky she was, and I loved her unique personality. You could definitely see the hatred she had towards the Capitol. And her attitude and personality and just everything just blew me away. I think Malone's performance was one of the best, if not the best, out of all of the actors.
On a last note about characters after that mini freak out, I don't know how I feel about how Mags was portrayed. I still loved her, and you could still understand her personality, but I didn't really like how she didn't talk. I know it was probably to get around the speech issue that I don't remember but was apparently in the books (you can see how much I didn't like the series in general...also it's been a long time).
Next, on to everything else. I loved the clock arena, and it was definitely freaky. I didn't really like that they didn't at least introduce all the tributes, which made it confusing when they showed the dead. I get that they weren't important, but I'm picky, and I couldn't stop thinking, "Did we ever see that person? Who is that?" I don't know if they were mentioned in the books, so maybe that's why, but still. But the arena was really well done in general. I also loved the Snow scenes, and the parts with his granddaughter were really well done. Caesar's scenes were hilarious as well.
I didn't really understand the huge jump in advanced technology. I get that it's the Quarter Quell, and I get that they had a much higher budget (the movie, I mean), but I don't know...it felt so weird to see such a vast difference in technology in, I believe, less than a year. I know it's not real and whatnot, and I do think that some of the technology did help to add to the movie and to make it look cooler, but I think the movie would have been just fine without that huge jump. Maybe I'm just being over picky.
The last nit-picky thing for me was the awkward scene cuts. It was definitely a lot better compared to The Hunger Games, but there were still a couple of times when this bothered me, particularly the one that cut abruptly from a dark scene to a light scene, making my eyes go WOAH NO.
In general, I really enjoyed this movie. As much as I'd hate to admit it, it's definitely one that I'd see again, and I think it was VERY well done. I would gladly freak out about the movie, as I have a bit already, just as long as you don't mention the book series to me (maybe Catching Fire is the exception but I don't really remember it) and push it in my face.
Basically, as a whole, I think the acting was phenomenal. Almost every actor brought something to their character, whether I personally enjoyed it or not. The pacing went well (if you don't mind that the arena lasted roughly 2 or 3 days and a lot of time was spent on everything before), and I loved the arena. The ending was perfect, and Katniss' facial expression? Awesome. Everyone really stepped it up a notch with this movie, and it really helped to make this epic. While I will never say that this is my favorite book-to-movie adaptation (despite its flaws, I'll always go with Harry Potter, and I'm not sorry about that. Argue with me all you want, but I will never let anything, especially THG, take over that spot. I'm stubborn that way), it's probably on my top ten list, as much as I'd hate to admit that.
Seriously, if you can, go watch it (if you haven't already). It will possibly almost blow your mind away by its greatness.