It is not available as a native app on any platform, but their mobile site works very well from my Android phone. I like to use my PC to add and organize tasks, because of the larger screen and actual keyboard. If perchance I am totally offline, the mobile version will still allow me to see my tasks, and if I make any changes, they will sync up when I am next online.
GQueues can integrate with Google Calendar, but I choose not to do that.
Why I like most about it is that it has a very clean look, so I can focus on my information instead of the pretty screen.