House of Leaves by Mark Z Danielewski

I read this book four years ago after checking it out from the library. I got a copy of it for Christmas and I'm thinking of reading it again.
Is there anything I should pay particular attention too as I read it a second time around? Is there something specific about the footnotes in the Zampano parts that I should look out for?
If anybody on /book/ has read this one before, which I'm guessing there are since this book is pretty popular, are there parts of this book that deserve further inspection and should I be leaving post-its at certain chapters?
Any input would be appreciated.

I have not read it, and have no judgement on it's quality.

yes!  there is a lot to pay attention to and look for.  the letters from johnny's mother contain encoded messages.  there are also hidden messages within the book like the authors name in one of the footnotes for example.  here's a good place to start http://markzdanielewski.info/features/guide/index.html