Perhaps the show would have been better off in an off-Broadway production, rather than in a Broadway production with the super-slick staging of Mike Nichols, but an off-Broadway production couldn't have offered Harris, Alan Alda, or Eddie Sauter's terrific orchestrations (which are preserved intact at Encores!, as original orchestrations usually are). And I've read that Nichols -- whose work I don't usually care for -- did a great job on this show, wowing the audience with staging tricks like having stage action play backwards as though in "rewind" mode.
Bock and Harnick wrote their own scripts for The Apple Tree, though Jerome Coopersmith is credited with additional dialogue. Whoever wrote Adam's closing speech from the first segment, many people consider it one of the most touching speeches ever written for a musical. I agree:
ADAM: Eve died today. I knew she would, of course. Well, at least her prayer was answered - she went first. Now that she's gone, I realize something I didn't realize before. I used to think it was a terrible tragedy when Eve and I had to leave the Garden. Now I know it really didn't matter. Because, wheresoever she was, there was Eden. And now, I have to go water her flowers. She loved them, you know.