We bought this toy for our daughter when she was 2. She is almost 4 and consistently plays with it still. The small parts are easy to lose, but we haven't had that issue yet, and the same is true for any puzzle.
My daughter loved this kit. The one problem we had was that the sticky goo that helps stick the gems to the bracelet kept getting left behind on the plastic. She had a blast doing it though, I just wish the quality of the pieces was a little better. I was able to pull to goop off the plastic and stick it to the gems, but that was a pain to do,