Thinks that are wrong and bad UI design in my opinion:

• the green and blue don't work at all together. Generally the coloring is quiet extravagant everywhere, especially with the message "this app has been built for an older version [...]"
• the spacings and margins aren't coherent everywhere. Like in the app description where the margin to the bottom is okey but to the sides it's much smaller and almost non-existent.
• the grid cells don't really stand out enough. White on White with such little shadown and spacing inbetween doesn't work.
• the animations are janky and unpolished.
• no support for Material UI 3
• buttons have too little padding inside around the icon. Buttons are generally a little too small