Amazing Marvin is by far the best to do app on the market. I´ve been using it for some months now and I´m still astonished by how easy it is to use as well as it´s huge functionality options. There are functions I´ve never seen anywhere before that make keeping track, planning and scheduling so much easier. All the reasons why I stopped using other to do apps over and over again - I haven´t seen any of them in Amazing Marvin by now.
There are some things that need some polishing (e.g. the android app, but as it´s working and useable, it´s just a minor thing for me), but the bottom line is: I´m really flashed by how Amazing Marvin helped me keep ahead of my work and to avoid overwhelm.
As this is a freeby here on appsumo. It´s a nobrainer to get it.