I would think a site where people can ask anything, ala stackoverflow, would yield more useful results for many physics/math/cs students.
That being said, I wouldn't take that as a reason to not pursue this.
So first year of uni tops, where most of calculus is still high school.
Similarly, if I go into the physics topics, they are all <= intro courses, at best. Optics? Doesn't talk about fourier optics, lasers, etc. E&M? Doesn't seem to mention Maxwell's Equations anywhere... enough said. Quantum mech? Nothing. Statistical mech? Nothing.
Okay, how about math? Take a look at the differential equations stuff. No higher order, no series methods, no numerical methods, no coupled systems, no non-linear. Probability? No markov chains, MCMC methods, or anything except basic RVs and statistics (which is not the same thing as probability). Same for linear algebra: no fitting methods, no matrix decomposition, no graph theory.
I could go on. The point is that they cover the most basic elements of each subject, and they miss a hell of a lot of important subjects. That's okay, but don't claim that they're anywhere close to being able to educate you at a university level.