Disclosure: Affiliate links.
I've seen a bunch of people mentioning that this subscription has finally "opened up," but it's not clear to me if it's available for everyone now or still just limited regions, but more of them. It has been gradually expanding for a while. I entered my email address at this link and got a message saying there were no spots left, but then I almost immediately got an email inviting me to subscribe. So if you've been waiting, it's worth a shot. Please let me know if it works.
I've been reading reviews of Play! for several months and it really looks like one of the better options available for $10/month--generally more interesting products and better sizes than Birchbox or Ipsy. Here is April's box (though I think if you sign up now you start with May), and here is a preview of May (not much info there yet). I'm not going to sign up just now, though, because I just bought a subscription to Choix (which I will review after I have got received two boxes and have more to say about it).