I like that it's easy to use since we are using this in our business so no need of training or anything else just start working right away! We have been able solve all problems related about telefonica services bills payments without any problem at least until now (which means not really).
It doesn't support other countries than Spain which makes things difficult when you're dealing internationally but still if your only concern here would probably work fine too even though there might some minor bugs regarding international transactions/bills payment etc.. Nothing specific yet except maybe its price could go down considering how much they charge per month compared what competitors offer us currently who has better prices by far!!