It was easy to implement in my app, I didn't have any problems with it at all! The code is very intuitive (I think there are some examples available), so everything works as expected by default - you don’t need too much configuration or setup before using this product fully-fledged without additional plugins/services etc., which makes life easier if used correctly from day 1 of implementation :) And best part? No payment required during beta testing phase!! Really awesome service.
If anyone needs quick & reliable solution that offers good user experience when implementing new features like sending out messages via SMS / MMS then definitely take their services into consideration! We use them mostly internally but we also implemented API integration within our apps' backend systems just recently :).