I feel the same way you do about this, Bobby. I've never seen a production, but I've become a fan of the score, which I think is adorable. From what I've read, the subject matter is a big part of the problem, as Danielm pointed out. The story is very dark. Mabel Normand started out as a popular and promising performer who wound up drug addicted and dead by her mid-thirties, and Mack Sennett was completely obsessed with making two-reelers, even after they'd become passe to the industry. Trying to create some sort of star-crossed lovers story out of this doesn't really work if you look at it in any realistic way.
Maybe those who have been in productions and made the book work as well as it could, could enlighten us about aspects of the show that really do work well. From what I've heard, Herman's wonderful score carries it along but to an unresolved and unsatisfactory conclusion.
"And the postman sighed as he scratched his head, you really rather thought she ought to be dead..."