updated June 23rd: I am signed up for the Public Beta, but it looks like you can get the Developer preview of iOS 10 NOW!
I tried out the Developer preview last week, but it was too buggy for me and a lot of apps crashed. I hear it works best on the iPhone 6S, and iPhone 6S Plus.
Have you tried it out? What do you think?
Also see: How to downgrade from iOS 10 back to iOS 9.3.x
Undercover Apple 