Ask HN: What merchant services/mobile payments company do you use?

We are getting ready to start accepting mobile payments for our business. I was wondering what others' experiences have been with the various mobile payments providers. I have been looking at Square and Intuit's GoPayment. Square looks like the better deal, but I've been reading horror stories online about businesses getting their money through them. Does anyone have any first hand experience with either provider? Does anyone have any alternatives they would recommend?