Their service is quite directed to customers in Forex tradings, that is they have lots of Forex companies as partners.
I have a few accounts with STICPAY, and have been using those periodically.
There are no problems so far... but you have to pay fees on any transactions (deposit, withdraw, sending between accounts, etc...), that will be quite high if you use a lot.
In general, they don't give IBANs to their customers.
Forex brokers have to be partnered with STICPAY if you use their transaction services, and I don't know if they accept unlicensed Forex brokers or not.
Just you can try.