I kind of liked the idea. Before, I don't really care about these stuffs, but when my brother had his child and our very first nephew in our family, we were ridiculously thrilled. Now I understand why parents throw out parties like these for their children. It's fun and you can be sure that the child would enjoy it too. Not only can they play around, they also get to hang out with other children as well.
On the business side, I would say that you may also consider pricing base on what the average salary in your area can afford as well as the demand. Maybe most big cities have this kind of service, but I'm not sure on smaller areas.