He worked with both novelist, Collins and Billy Ray on the screenplay adaptation.
Going in, you have to know that Collin's premise of 24 young people being forced to sacrifice themselves for the good of their nation, fighting each other to the death, down to the last one standing as their countrymen watch, is at once violent and disturbing.
Note despite the fact that there are tributes as young as 11 or 12 playing for their lives, the book is Young Adult; the film is PG-13. IMHO, parental guidance in this case should steer you away from bringing all but the most mature 10 and 11 year olds. It's not the violence quite so much (Ross's shaky camera work helps to soften some of the impact of the kills because you can't quite seem them clearly) as it is the fear factor.
For me, a very grown woman, my strings were completely manipulated by the relationship between Katniss and her younger sister, Prim. When Katniss volunteers and Prim has to be held back screaming, I was utterly moved. When Katniss befriends the youngest tribute in the arena, Rue, it is hard not to think of Prim. Melodrama is barely avoided but it is avoided and when Rue dies and Katniss suffers, we do as well.
For a younger child this could be something of a traumatic nightmarish occurence. Think Bambi!
But kids aside, the movie moves. Ross has taken the action - so much of it that is just heard about in the book - and given it onscreen life. Scenes of the action in the control room as technicians play with the tribute's lives as though they were virtual chess pieces are juxtaposed with moments down in the arena as Katniss and Peeta fight to stay alive.
Of course Katniss, talented with her bow, never kills if she can help it. She's our hero therefore she is noble. Jennifer Lawrence, plays Katniss beautifully. The emotions that play across her features still softened with babyfat are at once real and authentic. She's strong - this is her games to win, her movie to be the star of. Josh Hutcherson as Peeta plays second fiddle as the goodlooking and sensitive bakery boy with a Katniss crush quite well while handsome Liam Hemsworth's Gale does little more than watch the star crossed lovers on the big screen. I hope his character has more to do than cast his eyes downward in Catching Fire the second in the series! I haven't read it yet.
I posting the trailer again but I'm hating how much of the film it shows. Just go see it.