I'm a Bnos Chaya parent. I only have good things to say about it. Over the years things have been run smoothly, fantastic teaching staff, bullying/social issues addressed and taken care of right away.
It's a neutral chassidish crowd, comparable to TD or the (non stolin) Bais Bracha crowd.
I'm not sure how difficult it is to get in as my daughter started several years ago when the school was new and relatively unknown. They do have a strict internet and smartphone policy that you'll need to conform to.
Class size has fluctuated over the years as families move out of town and new kids are accepted. It's consistently been 22-26.