"Box modelling syndrome" refeers to the fact that the outlines of your polygonal loops follow the shape of the original box shape you used for the basis of your character. Edge loops should flow around and in direction of how the structure is shaped, this has many advantages, most pronounced for games chars being able to naturaly deform with minimal amount of info. Itrs one of those things you should avoid to do, never let the tool guide your work but rather let the intent guide your result.
You have this sortof halfway going in, but youve not realy finished that road, thsi is especialy apparent in the shoulder areas. Where yiou rematurely terminate the loops.
I have no problem with your shading as such, youd need better lightning if you wnated to show of something better.
