We recently changed our website design to use Google's Material Design. Quite a good number of long time clients had problems with the new forms layout.
Problems identified by us;
- Presented with a blank form; "I had to figure out where to click first. I'm used to the old forms". Problem here is the missing box border.
- The new forms seems to take more space than the flat design and the default ones.
For reference see:
Will you recommend material design in an application where you need to present users with a lot of forms? Considering some forms are a bit complex.