You have to be careful squatting to a box, or having any kind of surface stop you from butt to shoulders with bar on you, unless you have some experience and (or a little hands on coaching might help), since some people do not realize, you are pinning the spine between 2 hard surfaces if you hit or drop onto the box wrong or fatigued.
Personally, I think it is somewhat overrated for the vast majority, or especially raw lifters. One can get very very strong just doing reg BB squats to parallel, or nearly getting the top of the hip to knee level or below. Even pause squats to pins is a great strength builder.