I agree with you. I read the book series when it came out and I thought the movie did a bad job on showing the complexity of the relationships. I guess if I looked at the movie as a movie and not as a book, I would have thought it was great.
Read the books last year, saw the movie last week. I would (and did) re-read the books but wouldn't see the movie again. there were parts in the books that dragged too but it was easy to get thru.
You could only assume the importance of Gale in the movie due to the several shots of him brooding. I thought Haymitch should have looked more like a drunken homeless bum than Woody H. looked. You never got the feeling of how much the Games had destroyed Haymitch's life. The Avox girl gets a specific mention in the credit but played no role in the movie at all (Effie gives her an order once and that was it).
I was disappointed that they used cliches for the populations in the districts.
I also think they missed the mark badly when they had the Capital cut in before Katniss and Peeta had put the nightlock berries into their mouth (as they did in the book). You therefore miss how deadly serious everyone was at the end to get their own desired ending to the Games.
And not least, the jump shot camera moves (which I had read about before hand so thankfully I was prepared) made my motion sickness pop up a bit.
I think it was a harder movie to make though as alot of the 'action' occurs within the characters - and that is often hard to show on screen.