Read that.
I'm trying to read between the lines. What don't they offer?
Customer service
I looked into it 2 years ago when they came out, at the time there were a few issues. a) Lack of choice in phones, you basically had to pay for the phone they give you and then you can't use it elsewhere because it's locked. b) Zero customer service, they don't even have a phone number, all issues are expected to be resolved on the forums on their website. c) Some technical issues (IIRC there was no handover from wifi to regular calling, so if you started a call in your house and left your call dropped).