My Take
I think the idea is great. Students who want to improve, can benefit from it. Students that only want to complete an assignment, can randomly click or take all the hints to increase their chances of getting a right answer. It works well with students who need extra time to learn a concept or want to review.
How I Use It
I have only used the free version, so some things may be easier with the paid one. It takes a little time to get used to the set up procedures. I used it for remediation. If all students are entered first, you only have to select the assignments once. If you add students later, you have to reselect the assignments for each student.
You can see how long students spend on each question and what assistance they get. This is great information to use at parent conferences.