The basic differentiator is that you can set various constraints (e.g. "I want to spend 2 hours in the park", or "I have a dinner reservation at 6"), and Wherewhen will automatically adjust the rest of the times to tell you when to go/leave each place, including travel.
I've tried to make it mobile-friendly but travel planning is pretty complicated and it's a bit clunky on mobile.
Feedback is appreciated!