Great composition and very cute shot overall. Perhaps a bit on the dark side--it might be nice to bring out details in the black areas a tiny bit more--the girl on the left's dress, and their irises. And Happy New Year to you! (Oh, and the title at the top is not centered.)
You've captured a very cute moment here as the kids obviously look like they are having a good time. Although the lighting looks like direct flash, it does not look overly harsh as it normally does. A little bright on the hat, but you make due with what you have. I like your tight crop as well as it adds to the closeness between the two.
The one suggestion I would give you is to use the burn tool is some areas just to clean it up. Mainly the object in the upper left corner, the wisp of hair in the upper right, and the brighter spots on the boys shirt.
This is a cute shot, I would just love to see more light on their faces because the bright spot on the hat is so bright it catches the eye and distracts from their faces.
Okie dokie, here is the format I am going to use for comments this month :)
Composition: I really like the way you have them placed in the photo and the angle of the camera here. They look very close and it really brings in that sense of family.
Lighting/Exposure: Your exposure is good on their faces. I am guessing you used an onboard or hotshoe flash aimed right at the subjects. Camera attached flash really creates flat lighting if not used with some type of diffuser though. I see it in the really bright spot on the boy's hat. I do like that you managed to avoid shadowing on his eyes even with the hat on.
Pose: Again, the fact that they are touching here really brings this together, IMO. Both of their heads angled the same way makes for wonderful symmetry.
Suggestions for Improvements: For the lighting: Try using some type of opaque plastic and bending it around the flash. Perhaps secured with rubber bands. For PP: I would like to see softer catchlights in the eyes. This can be faked by using a soft round brush in PS and just painting over where the catchlights already are. For the pose: I would like to see more of her face. She is a cutie and should show it off. :)
Excellent action shot Steve!
No doubt they're having a lots of fun. I'm guessing they are siblings which makes for a perfect keepsake since they really do look like they are very good friends.