I've been trying it out for the past few months and here are the problems that I have encountered so far:
Students don't check their emails, students forget their passwords, students don't have computers at home, the school computer lab is always busy, Student change their use names and you don't know which student submitted work, etc....
If you use Google Forms for assignments, you are pretty much limited to multiple choice answers, as the other answer formats have some limitations (I teach Science and don't penalize students for spelling, Google Forms quizzes only accept correct spelling.)
On the plus side, you can link to videos, give them copies of late assignments, post copies of you powerpoint presentations, send messages to students who haven't turned in work, etc...
I was using it with my P5 students and I found that they really weren't ready for it. I will try M1,2 & 3 after the NY break and will see if they respond better.