I have to question the premise of such a service. The statements in the "Why Sunsama?" section are comically grandiose. I sincerely doubt that people who are "struggling to keep up" are hindered primarily by poor scheduling or, if they are, that they will listen to reminders coming from yet-another piece of software or that the software will magically know how best to prioritize tasks. Based on these claims, I would easily toss this product in the "snake oil" category of products and services which promise to make my life awesome but which, at best, might make a marginal improvement. If there is more to the software, awesome, but that should be front-and-center because as it stands I see no real value proposition.
Thanks for being so frank. Perhaps that section needs to be re-written since Sunsama doesn't do reminders or use any sort of any algorithm to prioritize your tasks. Instead, we provide a guided daily planning workflow that nudges the user to make good decisions about what to do. In fact, one thing we feel strongly about is that you will make a better decision about what to work on than an algorithm.