Heard it wasn't very good.
Even an NPR critic pointed out the film used the book poorly. For instance, he illustrates that there's a scene in which Ted (The main character of the film, a nameless boy in the book) is listening as Audrey (His apparent love interest) tells him about what the truffula trees were like, using their description from the book, "the touch of their tufts was much softer than silk and they had the sweet smell of fresh butterfly milk." In the film, Ted says, "Wow, what does that even mean?", and Audrey responds, "I know, right?"
So, as the critic points out, one of the only lines from the book that is actually used in the movie is essentially made fun of. I'd imagine it would be the equivalent of one of the film's writers bringing Theodore Geisel back from the dead just long enough to tell him, "What you wrote sucks and makes no sense, I'll make it funny!"
I won't even use my free movie pass that I got donating blood on it, I think if 21 Jump Street remains in theaters after Easter (I gave up R- rated films for Lent), I'll use it on that.