Their back-end portal is fantastic with the call filtering options to prevent spam, re-route calls, free incoming/outgoing SIP, free voicemail. The list of features is outstanding.
My favorite feature is the call filtering. They even support wilcard numbers which add a granularity to the service that I find very useful.
They are rated as the best VOIP provider on DSLR. -- ...virtue gives you heraldry.
Their website is lacking any functionality, products or ordering. They also have multiple 404 errors on their site. Not very promising at this point. Even though it's only 5$ they should still try and sell their product a bit better.