My Take
Overall this is not a bad site. I like that it offers many subjects including english, math, chemistry, languages, anatomy, and SAT prep to name a few. This helps to give students a variety so they aren't stuck doing the same thing every time. I also like on it allows teachers to view student progress and gauges the level of difficulty on how questions are answered. This tailors each lesson to a student's specific need. One downside is it is very repetitive and students may get bored with the drill and kill method.
How I Use It
With the large number of subjects I teach this is a tool I can use in all of my classes. I enjoy that I can monitor how my students are doing and depending on how they answered the questions get easier or harder. With the variety of subjects my students can build up on all of their skills. One downside is that it is only very basic and students may get tired of it if it is used on a regular basis. It's something I would do once a week in my class.