I found it charming, but lightweight. The best, emotionally engaging moment was "This Was Me"... which, I gather, wasn't even in the original show. I feel like "He's My Boy" should have been an emotional high point, but was undercut by taking the focus off of the mother and effectively turning it into background music. Sarah Lancashire and Richard E. Grant did their darnedest to elevate the material—mostly successfully. Harwood was convincingly teenagery. Ahem. ;)
Treads some of the same ground as Billy Elliot—but IMHO the latter is a better piece of theatre.