All in all, it is a good device. I like that they are geared towards children, because my kids would not ever wear a plain one. In fact, that is the main reason we went with the Garmin... that and the fact that the battery does not have to be charged.
My 5 year old LOVES his. In fact, he's driving us nuts wanting to know how many steps we have (Hubby and I both have Fitbits, so we can't compete through the apps). It would also be really nice if there was a way for the app to read the instructions, instead of the child having to read them. My 5 year old is fine, but my 3 year old cannot yet read, so she isn't so much in to the app because she doesn't know what's going on.
He seems to get around on it fine and we're soon going to start implementing the chore rewards.
Other than that, we have been pleased. We got the adjustable band. For my 5 year old (and 3 year old) the smallest setting works fine on the adjustable band.
Overall, we've been very pleased!