If you decide to use them to buy bitcoins, always immediately withdraw those bitcoins to a real wallet.
They set up circle to operate as a "bitcoin bank." And what do banks do? Play with your money.
I think some people who do not understand technology will like the idea of a Bitcoin bank. They do not get the idea that you can and should be your own bank.
If you do not have the private key for your Bitcoin then you have no Bitcoin - you do have, at best, a Promise to Pay (an IOU).