The section on hue-shifting was really good, and would be some really helpful advice for artists who struggle with colour or are new to colour work! 
Overall I felt like it was a pretty good grounding in the basics, and the only thing I'd add would be a mention of something like how value can be used to create depth, maybe with examples illustrating scenes where the environment fades off into darkness or into hazy light with distance.
Some more examples of the different colour schemes (triadic etc) used rather than one each might be good?