I like that its very bare bones and not cluttered. The installation is also very small unlike photoshop which is in the Gigabytes! Medibang clocks in at about 135 Mb when I first installed.
The app comes with Simple brushes but effective. You can customize them easily through the Brush panel.
It has everything you need to make paintings or concepts just using Layers, Brushes and a color selector.
It works on PC / MAC / iOS and Android. I have not tested out the mobile version but it seems good that they are on a few platforms for you to try it.
You can save to the cloud. if you want to for your project and it can link up with a few iOS and Android Apps to aid you in the creation of your comic or manga.
Found a short video from Sycra.