I just read through the Preface and it reads very well.

However, I found three small issues.

On page 1 at the bottom there is "Seasideweb development" which I guess should read "Seaside web development".

On page 2 there is "MacOSX" as supported platform which Apple renamed to "OS X" some time ago (OS X instead of MacOSX: https://en.wikipedia.org/wiki/OS_X).

Also on page 2 I read the sentence "You can make an impact on Pharo" but to me it was not really obvious how this sentence relates to the paragraph it belongs to or how you actually can make an impact on Pharo.

Hope this helps,

Manfred