Charming though they are, each denizen of the ''Peanuts'' comic strip has a failing. Charlie Brown is wishy-washy. Lucy has a nasty streak. Linus is insecure. And even Snoopy, the world's most beloved beagle, has an oversized ego that's not immune to delusions of grandeur.
Such lapses are largely absent from the new musical that bears Snoopy's name. It's a happy little show, full of songs and jokes based on thoroughly tested ''Peanuts'' formulas. True, the characterizations and repartee looked a lot fresher when ''You're a Good Man, Charlie Brown'' first brought ''Peanuts'' to the stage in 1967. But there's life in the old gags yet, and ''Snoopy'' charms even when it doesn't surprise. It opened recently at the Lamb's Theater.
As the title character, David Garrison contributes the most energy, whether envisioning himself as a world-famous novelist or pining for the good old days on the Daisy Hill Puppy Farm. Deborah Graham stands out as Sally Brown, partnered by Kay Cole as Lucy and Vicki Lewis as Peppermint Patty. Stephen Fenning is a credible Linus, though Terry Kirwin seems too fresh-faced as Charlie Brown and doesn't wear the right kind of shirt. Cathy Cahn flutters about the stage as a properly maladroit Woodstock.
My main quarrel with ''Snoopy'' is that it quotes too literally from the comic strip; my 11-year-old companions muttered many of the punch lines right along with the performers. We all would have enjoyed the show more if its material were new, or if there were a solid story to pull the musical numbers along. Yet the ''Peanuts'' gang is still fun to encounter, and Snoopy remains the king of pop-culture canines.