http://www.wired.co.uk/article/facebook-messenger-pay-uk-how-to-wechat
It sounded quite nice until this:
“The money is then transferred to a friend in one to three business days. If the friend hasn’t set the system up, they’ll be prompted to enter the card details to get the payment.”
It sounded quite nice until this:
3 days? Why would anyone use it?
I agree. Facebook - the bastions of data privacy! 
it’s worse than BACS! At least with BACS your data isn’t being shared with a huge US corporation… 
Also, on another note. The Messenger app has become more and more bloated, with Snapchat style features and special bot channels etc. etc. I only use as a communication tool and so do most of its users I guess. i now use the Lite version as it gets rid of all the crap and turns it back into just a messaging app. Yes the experience isn’t that great and I don’t get “secret” conversations (but I would use Signal for anything vaguely important anyway) but it doesn’t use as much battery and you don’t get a load of extra stuff slowing everything down.
I tried to switch to the lite version but it seemed to require a full Facebook account and I only have a messenger account.
3 days 
Even paypal is pretty instant now. DOA.