1. You’re trying to sell something, but you make us hunt for the “buy” button. Why not make it big and orange? Why?!
2. I have to create an account before I am allowed to pay you? Think dammit. You sold me. I have my credit card in my hand. Are you really going to now put hurdles in my way?
3. There is no way for us to send you feedback. And I had cool suggestions for improving your site/service/product. I would have given them to you for free.
4. You have a feedback form, but just like your order form it is hidden behind a login. Useful feedback from real users is rare and valuable. If you require a login, expect none.