I have bought several of them for my DD. The quality is not as good as GK but they are also not priced like GK. For the price I am very happy with the quality! I feel that they are sized a good bit larger then the GK's (at least in the smaller sizes). In GK my DD wears CS for competition fit and CM in growing room fit. In JillyBeans she is still wearing several of her CXS leos and her CS still have plenty of room. At this point, I can not speak on the larger sizes. I think my DD has 7 Jillybean leotards so that should say something about how I feel about them.
I bought my DD the JillyBeans Pirate leo over the summer for Pirate Day at camp. We usually get a GK AXS to allow for a little growing room. We ordered an AXS from JillyBeans and it was perfect. We are very satisfied with the quality and loved the fact that we only $14.99 for it!