Yeah I've used Omnifocus and it's fantastic but being extremely limited to the Apple platforms along with a mediocre sync I'm surprised they've been able to stay afloat without branching into other platforms.

I spent far too much time using Omnifocus only to be forced to use a PC due to changing jobs and not being able to access even a read only version of my tasks, something I need in daily life, is just unacceptable. My opinion of course but I can't go back to them. I do miss the calendar view though.