We have been using one for a few months now (much of the time while it was still in beta). It has been really awesome for us. We have about 1500 retail stores, and moved that to be our VPN hub so that AWS resources can VPN to all of our stores. It has been a huge game changer for our organization.
We are also using it as our primary VPN between our main office and our AWS infrastructure now, and it has been really awesome for that too. Much easier to set up than the direct VPN built in to AWS.