I picked this up last Autumn and finally finished it last night. But that isn't because it was a "difficult or "long" read. This is basically a summary of John's journal entries for one year. It is a good exercise to write down what you say to God, because it seems that it is easier for some people to hear God. I tried it, at the suggestion of John early in this book, and it does work for me.
Too often, as a Christian I "know" that God hears my prayers, but I rarely would actually, actively, listen for God to answer my prayers. I know He answers through His Word, through the creation - to a lesser extent - and through other people and situations. But now I'm listening more intently and I've found that God is there, speaking to me.
Writing that last sentence feels kind of weird for a mainline conservative protestant like me, but it is also liberating in some way.
If you like John's books, definitely pick this one up.