The show had a terrific score by Clark Gesner -- who also largely wrote the book, taking much of the text from Peanuts strips, but remarkably he chose to use a pseudonym for that, "John Gordon." He apparently felt that since so much of it was Charles Schultz's words, and there were some others who had input, he didn't want to take credit. Which is halfway between admirable and unbelievable.
The show was originally an off-Broadway production, where it had a huge run for 1,597 performances, almost four years. It later transferred to Broadway, though it didn't last all that long there. The revival in 1999 added a few news songs by a different composer Andrew Lippa, which I didn't find had quite the same charm, though "My Philosophy," was very good, and the song introduced Kristin Chenoweth who won a Tony Award as Best Supporting Actress. It only ran for 149 performances.
The original production had a terrific cast, the best known of who was Gary Burghoff as Charlie Brown, later best known for playing Radar O'Reilly on M*A*S*H. Other notables in the cast were Bob Balaban as Linus, and Reva Rose as Lucy.
And there's another nice bonus. In the opening credits, you'll see that Clark Gesner finally got full credit for writing the book.