We tried it and I had high hopes, and it was easy to use, and I really liked the scope and sequence and thoroughness of each subject. However, my kids really didn't warm to the style. I thought at least my son would, because he normally seems to like sarcastic / gross humor and spastic animations, but for some reason, this quickly seemed shallow to him.
For my daughter, the sarcastic humor was a total turnoff. But then, she also finds things aimed at the tween/teen demographic rather tiresome in general, because she doesn't resonate with eye-rolling, complaining, the "adults are the enemy" meme, or with slapstick and physical humor or the art of the put-down.
If Disney shows and the popularity of recent movies like Judy Moody and the Not-Bummer Summer, the new Ramona movie, shows like Labrats, etc. are any indication, there are far more tweens and teens who like that kind of thing, than object to it, so the best way to know if you'll like it, is to try it.
If your kid likes it and learns from it, it is extremely easy to use, for the parent, and has convenient reporting.