I don't think that's really the books fault as much as it is Haskells. I also think it's why you hear ALOT of people swearing Haskell is actually very easy, because everything up to chapter 9 is not very complicated at all.
I'm sure there are some very tallented people where this isn't true, but I get the impression that the people who are saying it's easy haven't gotten to the point where you can actually do things with Haskell, or developed a program with Haskell, or inter-operate with other libraries using Haskell, or tested their metal against the Parsing Combinators in Haskell (let alone making your own set), or ect. ect. ect.
Chapters 1-8 aren't complicated in the slightest.
Chapter 9 is when it starts.
Haskell isn't easy.