I like the range of expression here. My only pick is that the middle portrait seems to have a different colour toning which looks a bit out of place amid the others.
nice collage, but I think the backgrounds and lighting should be the same in every photo if you present it like this. especially the whitebalance doesn't seem consistence.
Fun... I have a similar collection of images from my daughter that I call "The Many Faces of Angie". She's quite expressive. You've captured some good expressions here as well. :-)