I thought I'd be less controversial for a change and say I am actually pretty impressed with the API link to a Monzo current account.
Just need a business account from them now. We could build services around instant fast payment to us I am sure.
P.S. I am testing BACS and DDs to see how they work, do I get a ka'ching at midnight or something. BACS is all batch date based, so will be interesting to see.