The only aspect of the criticism that I think has any validity is the thematic one -- in the book, there is a dynamic of the Capitol literally "fattening up" the tributes before sending them to the slaughter. At one point just prior to the Games, Katniss looks in the mirror and almost doesn't recognize herself, in part due to the prep team's "beautification" and in part due to having gained weight and muscle due to the food and training. (As I recall, I think she notices that she can't see her ribs anymore, or something along those lines.) Then Katniss again loses weight during the Games, to the point that Cinna tells her at the end that he put a padded/pushup bra in her dress because the others wanted to give her implants to fill her bustline back out.
By not showing any physical change in Katniss from District 12 to the Capitol to the end of the Games, this aspect of the Capitol's brutality is lost. That said, they can't include everything from the book in the movie, and there are plenty of other examples of the Capitol's evil streak to make the point.
"Okay, if you're going to question the importance of an actor's signature on a plastic helmet from a movie based on a comic book, then all of our lives have no meaning." ~ The Big Bang Theory