My Take
It is not that helpful and I think quill is useless. I am from the UK and it uses American English, which confuses students. I do not recommend it.
How I Use It
I use this with my year 9 class every Friday. They despise quill and hate doing it every Friday. Unfortunately for them, it is curriculum in our school and so I can not do much about. It puts the students down as well. If you get 1 wrong then you get told you are not proficient.