I really really really Material design

I like that they make me think about things like depth to differentiate what's active , I like the little line in inputs ,it encourages users(me included) to fill the input,

the ripple effect is small and cheap animation and communicates to the user a click .as is with checkbox etc

the morphing transitions is their best idea , As a user I hate flickers , if you blink you miss them overlay are even worse unless you are alerting.