Thanks for all the comments on my previous post. I think I am going to take all the advice, in one way or another! I have decided to keep reading "Heaven", but to skim it for the next 10 chapters or so. If it doesn't get any better, than I will put it away for good.
As for the Piper book, I have decided to shelve that one for the time being. I can always pick it up again when I need the message (that is, when I'm struggling to desire God) or lend it to a friend who may need it.
Sometimes you know the right answer, but you just need someone to validate that it is ok! Thanks everyone!