I've made about a dozen payments with them, and have had only one real problem - not long after I made the account but after I'd used them successfully for a few payments, I was paying for a purchase in 2 payments (one for each item).

After making the first payment, Wise decided that they had to see my passport before I could make any other payments, so I had to call my wife at home in another city, have her scan in my passport so I could upload it for verification and then still had to wait overnight until they unlocked my account. I asked customer service if they could allow my second payment while they verified my ID, but they said they said I had to wait but "it won't be long".