Thoughts from a 5 year old: It may sound like a simplistic concept but my son loved it. He was challenged to re-create the images and would spend hours (seriously, hours) playing this app. He would proudly show me just how many he had completed and I marveled at how hard he would work to accomplish each one.
Thoughts from a 2 year old: While he didn't get the idea of re-creating the image, he did enjoy designing his own grid style artwork. It would keep his attention for short stretches of time. This app is definitely better for children 4+.
Mom's Take: I thought it was pretty cool how much it made my son think and found it to be a good way for him to use his mind creatively. I was completely shocked by just how long it could keep his attention! As for me - the puzzles were a little too simplistic.
Simply Stated: If you have a child in the 4+ range this one is a great app for them. It reminds a me a bit of those cards you used to get in kindergarten with an image made from shapes and then you would try to duplicate it. Good brain work :)