My Take
This is a great tool for a pre or post assessment. It gives the teacher and the students immediate feedback. The teacher can use this tool to assess understanding and modify teaching as needed, The free tool has limitations, but usually can be used effectively in the classroom. The paid version is powerful, but can be expensive because of the per pupil cost.
How I Use It
As a Principal I use this product with staff as a professional development tool. Also, to model tools they can use in their classrooms.