If you count yourself among those that saw the 1989 Oscar winning film by the same name staring Morgan Freeman and Jessica Tandy, you're probably going to have the same reaction to the play that I did. "So that's it"?
I can't say I know the original play, but I can tell you that it is most probably pretty similar to this incarnation, its Broadway debut, than the movie. The original play was part of a trilogy written by Alfred Uhry named the Atlanta Trilogy which dealt with Jewish residents of the aforementioned city in the early 20th century. The movie certainly had a more sentimental, gentle, and quaint appeal. As with many works that go from stage to screen, Driving Miss Daisy gained a great deal of cinematographic depth and character development that would never be possible on stage. The play, as presented, is a series of vignettes - seemingly more detached than the flow on the big screen - certainly less colorful and much here is left up to the imagination, including the car itself - represented by merely a chair, a bench and the skeleton of a steering wheel. 
While it was the treat of a lifetime to see these two national treasures (James Earl Jones and Vanessa Redgrave) on stage together for the first time, I must admit that I thought it was more about the strategy of putting these two mega-starts together to perform, not necessarily fulfilling the author's intent of a much younger Hoke to the more elderly Miss Daisy. That aside, not a second passed that the two of them, aptly complimented by 4 time Tony award winner, Boyd Gaines, failed to delight.
As movies go - this one was top notch. It's hard to beat that on stage the second time around.