The big advantage is of course that it is relatively anonymous, apart from the KYC. You can deposit as much money as you want, there is no one to check or view a transaction and possibly put it on pause as banks often like to do. And it also goes very fast, you can gamble fairly quickly on the site after an upgrade. And for a payout it is of course exactly the same story. Anonymity could also be a disadvantage if you have problems with a casino.