I read this book many years ago and really liked it. In fact, it's the only John Grisham book that I thought was worth recommending to someone.

So I watched the movie last night. First of all, I was SHOCKED when I saw they made a major change. The book is geared around a case against the Tobacco industry while the movie changes it to be against a gun manufacturer. They did ok with the change, however some of the scenes that "worked" when put in regards to the tobacco industry just didnt seem to flow in the gun context.
I think they did put one reference to the tobacco thing in at the very beginning with the lead character asks another person "Dont you know those things are bad for you?" in reference to smoking.

Regardless, the movie was decent. John Cusak did a good job portraying the lead character, Nicholas Easter. Incidentally, when reading the book, I always pictured Nicholas Easter as being Matt Damon.

I would probably recommend the book over the movie, but if you dont wanna read...then see the movie.