Easy to use
Easy to use, feels secure. Real mid-market exchange rates and very transparent, low fees. Transfers happen as fast as the respective banking systems will allow (usually very fast!). I’m a satisfied regular customer.
My only small complaint would be the fees for transfers within the same currency/country, which would normally be free at a traditional bank. Especially transfers from your euro balance (held in Belgium) to an EU account. Inter-EU payments should always be free.