First it is free although there appears to be an option to upgrade to premium services. I don't see where it is necessary to upgrade as I was able to play the games and earn tokens on the free version.
Second it appears to be fairly safe with various safety measures in place. When I first registered it asked me for my "parents" email address to register. It then emailed the parents email for permission to join the site. Obviously any smart kid would know how to get past this but I do give them kuddos for trying. Also for safety they have 2 levels the parent can choose from when it comes to chat. One lets them have basically complete freedom while another limits the type of words and such that can be used. So for a parent setting up the account you can try to be sure your child won't be exposed to foul language and such.
Third there are a decent amount of options available. The player can participate in baseball, snowboarding, and basketball. Games centered around the sports teams due to partnerships with MLB.com and NBA.com I'm sure.
Overall it's a neat little game community for those younger kids who would like to participate in online games but who aren't quite ready for the more adult geared versions.