It does sometimes take two business days to clear, so it's not good if your service requires fast turnaround (e.g. pizza delivery). Of course, it's always good to have another option, and perhaps even for pizza delivery you could accept it on trust with customers you have a good relationship with.

(On the software side, unlike a credit card payment, this does require that you temporally decouple ordering and billing. Besides the processing delay, a lazy user might not send the payment immediately. Two weeks seems to be a typical length of time, and of course you don't ship anything until payment is received. Treat it a bit like a cash-by-mail payment.)