The value of her life cannot be measured by how long it lasts, any more than the show's can by how long it runs. Which is not to say she or it is a downer. Far from it: Though an underground river of sorrow gives 'Kimberly Akimbo' its keenness, the surface is shiny comedy. That was already the case in the play by David Lindsay-Abaire on which it is based, a play that begins, as the musical does, with a visual joke: a grown-looking woman, outside a skating rink, dressed like a teenager and nibbling a candy necklace. That's upbeat Kimberly, as usual trying to make the best of life's bad situation. And now, with the addition of songs (music by Jeanine Tesori; lyrics by Lindsay-Abaire) that turn the carpe diem dial to maximum, the director Jessica Stone has turned up the hilarity dial as well, to keep all that emotion in balance.