The flexibility to customize our own look/feel has been wonderful! They are easy enought o communicate through without issues or problems so far as I can tell? Not much - just have some minor customization needs but they've helped us get around them in ways we didn't anticipate when designing it ourselves (like adding additional fields).
We had no major complaints about their service thus far though! Very friendly team who were quick at helping me resolve any questions / concerns regarding my experience using this platform.