Service works. That's about it.
When in Slovenia, you don't really have many mobile operators to choose from. Simobil's service generally works (not everywhere though), and there are no bigger issues, if you pay your bills and don't complain. Once you start dealing with the customer service, it becomes a terrible experience.
They are reluctant to reimburse money for the errors they make, in my case, they made two different errors on two occasions, and it took more than a month to prove that they were in breach of our contract. The call centre had some very unpleasant people, one of them didn't really make an effort to help me, but repeated the same sentences over and over again, causing frustration on both sides of the telephone line. Would recommend using another service.