I strongly disagree. It is far more simple than C!
While the reader might benefit from additional HDL examples in the text, part of the principals behind the book are hacking and exploring. As such, I feel that there's just enough HDL information in there to get you going, and enough hints to discover. You just need to spend time with this stuff.
I had never written HDL before attempting these problems and now I am just a couple short of finishing all of the first chapter, I really don't think the "language" is at all the hard part. Do you have any specific problems?
Remember to walk through the presentations on the Software page to get to know how to go about using it.
The biggest problem I ran into was trying to thinking of it in terms of high level programming. I kept wanting to use loops, set variables, etc. Once I forced myself to think in terms of incoming and outgoing bits, this language is extremely easy. Fundamentally you only need to know the basic logic gates and that is your entire language. The rest you can build up yourself.