I used to use them, and I had two issues:

1. Their international plan is garbage, and if you don’t use the international plan, you cannot usefully use them as a phone-and-SMS-over-WiFi only solution in conjunction with another carrier. Competitors like USMobile do not have this problem.

2. Their customer support and website are very bad.

SMS works over WiFi? Or is that only RCS? Not familiar with this