One of my favorite poses in the Achat, not that my limited experience matters all that much, even if it looks like it would hurt irl.
It does you need to be very flexible for it personally i prefer the guy being on his side with me rather then like this (in the flexy girl pic) far easier.
I am flexible enough to do this irl but prefer other possies. I would recommend anyone trying that for the first time does the background work of yoga and working on your flexibility first.