Well done, very well written!
Be aware that the approach this book takes has its own type of target audience. I guess the audience that will like this book/tutorial are the kind of people that will usually just read the entire reference manual of anything to see what's in their toolbox before actually starting to build something. So by reading it, you help them as a guide to work through it, choosing the parts of the language that are best learned first. After following the exercises, the reader can already build some programs using those concepts, whatever it might be, leaving it to their own imagination.
The other type of audience, which this book might be less suited for, is people who get bored after chapter 1, thinking "I want to build something fun now already!". Those might be better served by a tutorial like "we're building a XYZ game", explaining concepts along the way.
Both are good, both are needed.
I'm one of the first type of people, so I'm really happy to see this kind of book. The second type of tutorials only give me fragments of information if I follow it building that XYZ game, while I have my own idea of what to build, and just want to learn how those lists and dictionaries work when I discover I need them. ;-]