In no apparent order...
1. It's very apparent that Suzanne Collins was involved in fashioning the screenplay. The changes that had to be made to the story in order to adapt it to the "big screen" make sense and hold true to the spirit of the books.
A few of those changes are...
-- The origin of the mockingjay pin has changed. Katniss picks it up in The Hob as a good luck charm for Prim, because Prim is frightened of The Reaping. Prim in turn gives it back to Katniss for her protection once Katniss volunteers as tribute.
-- After Katniss brings the flowers to Rue, the people of District 11 salute her, but they don't send bread. This is one of my favorite moments in the novel, so I was waiting for it, but I ended up being thoroughly satisfied by what substitutes in its place: a chilling glimpse of the riots as they begin in District 11. I understand why this was done, and it is extremely effective.
-- The muttations in the arena no longer have the faces of individual tributes. Believe me, I was grateful. There's plenty of violence to make this feel gritty and desperate, and the film gives us several "behind the scenes with Seneca Crane" glimpses into how manipulated and intentional the dangers are, so it would've been rather redundant. Furthermore, after Amandla Stenberg's brief but unforgettable turn as Rue, I really, really didn't want to see her face on one of those creatures.
-- Peeta's leg injury is dire mostly due to infection, but it's mostly healed by the medicine Katniss picks up at The Feast. He doesn't end up losing it.
2. There are some lovely additions that set the stage for the next film, most of which are short, intense scenes with either/both Seneca Crane or/and President Snow. Donald Sutherland's performance in particular looms large over the picture. Perfect casting there.
Speaking of casting...
3. I can't criticize any of it. Josh Hutcherson is Peeta down to the last breath. Although I originally cast Brendan Gleeson in my head as Haymitch when I read the books, Woody Harrelson completely won me over. Jennifer Lawrence is subtle, understated, and just right. Stanley Tucci steals every scene in which he appears. I initially had reservations about Lenny Kravitz's ability to project the warmth necessary for Cinna, but I shouldn't have worried. And Amandla Stenberg is everything she needed to be.
4. I'd read reviews that suggested the director (or someone, at least) was "Team Gale," and Katniss and Peeta have no chemistry. I disagree. Liam Hemsworth is not at all the man I pictured when I read about Gale, and I'm still not entirely convinced of him as a black-market hunter/trader, but his Gale does have undeniable sparks with Katniss (and a great relationship with little Prim, too). That said, I was sold on the genuineness of Peeta's feelings, as well. The lack of immediate connection between Peeta and Katniss seems absolutely spot-on, considering the fact they are - or, at least, Katniss is - negotiating a tricky "performance" for the spectators and potential donors, always aware of being watched and uncertain of how much from the other is feigned and how much is genuine. The Katniss-Peeta "dance" feels quite authentic.
5. The action isn't sanitized, but it's also not glorified or overdone. I was in a packed theater filled with people who obviously knew the book, and still there were audible gasps at several of the deaths, these scenes were done so well and shockingly. I don't think the film loses dramatic potency for being edited down from the R rating to a PG-13.
6. I wouldn't want to meet Clove in a dark alley. I'm just sayin'.
7. The Orwellian imagery throughout (including President Snow's propaganda film shown before the Reaping and the omnipresence of the Peacekeepers) strongly complements the political themes of the story.
8. I only have a couple of minor complaints:
-- The "shaky cam" phenomenon (to which I'm usually immune - I had no trouble with The Blair Witch Project or Cloverfield) was over the top at the beginning of the film, to the point I wanted to close my eyes. Fortunately, the camera work became friendlier as the film progressed.
-- At several times during scenes in the Capitol (specifically the chariot scene and the tribute interviews), there was quite an obvious discrepancy between the wide CGI-enhanced shots (wow, look at all of those people in that wide-open space!) and the close shots (wow, there are only a couple of hundred extras jammed onto a set!).
On the whole, I'm quite impressed with the movie. I'm anxious to see it again soon.
I'd be interested to hear other reactions to and thoughts about the film!
PS. The Songs from District 12 and Beyond album is quite good!