I think when he described them as boxes and blocks, he didn't mean to imply strictly perfect geometrical cubes. The red and green blocky objects come across as having chamfered or beveled edges, while the blue ones clearly have a front face that extrudes to a point. The boxes and crates are perfectly readable as well. The lighting seems accurate to me, and I also love the vibrant colors, cute piece overall.
Cubes tend to be symmetrical in every point, but the red and the green ones have cut edges on their top and bottom, whereas the other two sides are flat till the edge.
And if those lines of different colours are supposed to be shades, you should know that shades are impossible on flat surfaces (not shadows :) ). Anyway, there`s either assymmetry or lightning mistake.
To explain the shading, here's how I imagined the color blocks in 3D (sorta):
i.imgur.com/GPeL3u3.gif