It introduces Haskell basics in a nice manner, pace and order. The author appreciates visual diagrams to describe typeclasses functionality and relations, which could help newcomers. With that, it covers truly a lot of Haskell core concepts in one book. It couldn't replace a course of Haskell for sure, but none of the books can, if you read just a single one and without exercise.
And finally, and possibly a spoiler here, the author leads to the conclusion that nodes in visual programming are just function Arrows (while perfectly explaining Arrows)—even in a much simpler way, than I could have expected. So this book provided me with a bunch of inspiring ideas for Noodle :).