FANTASTIC for a free program!
I think it's an excellent way to integrate grammar instruction that gives students immediate feedback and allows me to create the "pack" they work on for the week.
The only thing I wish was different was the feedback is only given to them as proficient, near, and not proficient; I give an average for the packs, and students have to come to me repeatedly for the numerical avg.
How I Use It
I use this with my 8th graders, inclusion through advanced. I like the pretest, the fact that you can assign activities based on their gaps. I use it as a warmup in my ELA classes to be able to stop and do mini-lessons on problems that I see being repeated in the class. It's awesome immediate feedback and gets my students thinking about grammar rules/spelling they haven't had to remember because of Grammarly or spellcheck on their phones.