I didn't have any problems setting up a click and buy account. The only thing semi- inconvenient about it was my bank calling me to verify that a foreign company was trying to charge money on my credit card to establish my click and buy account, which wasn't very inconvenient.
If I need to provide them with a written notice for cancellation that seems fine to me. Also they haven't done anything shady to me yet as far as my credit card statement records go. Everything went pretty smoothly when I bought Crysta through Click and Buy for the Tokyo relief donation.
Doesn't seem like a big deal to me yet.