I saw a regional production of this show over the weekend at Seven Angels Theatre in Waterbury, CT. Rob Bartlett (who I've seen on Broadway in Little Shop, Odd Couple, and How to Succeed) played the Walter Matthau role.
The show is bland and inoffensive, with a pretty forgettable score. The two best numbers are one where the grumpy old men debate the best "way to go" and a Chicago parody with an IRS agent. The randy grandpa character is also a highlight, he gets the best lines in the book.
This musical shows the limits and perils of adaptation, however. The team added a character named "Punky" who's one of the most annoying stage creations I've ever come across. Her big number falls completely flat, dragging down an otherwise pleasant afternoon.