Looks good and all, but Sakura is too tall compared to Naruto and Saske. She appears older then both of them..

They are both sitting down you know.

It's called a perspective.
Sakura's in the foreground, she looks slightly larger for a reason.

No, Bradley's right, the boys definitely look younger. Especially Naruto, he looks like a little brat.
If you look at Sakura's position, she can't be closer than the ninjas sitting on the grass, and they seem to be having a picnic right under the tree. To have a view broad enough to encompass the entire scene, the observer has to be quite far. At that distance, putting Sakura one or two metres closer does not account for that size difference at all.

tl;dr: artist fails at perspective.

I'm in no way familiar with Naruto, but I was assuming that those were kids in the tree, like some sort of "next generation" thing. I thought we were comparing Sakura to those two on the ground.