Disclaimer: I've never seen My Fair Lady although I'm thoroughly familiar with the premise. This means I can't accurately comment on how accurate the authors' representations of the characters are.
So saying, there was a lot to like about this book: the writing was smooth, the pacing consistent and the mystery plotting was excellent. Everything about the book held my attention... until the last scene. It started out well enough, but slowly became eye-rolling; after a brief interlude of plausibility, it freight-trained straight into slapstick, where the authors outdid themselves and pushed straight on through to ludicrous. If their editor cared about them at all, he or she would have ripped out and shredded all the pages after the secondary character, Roz, stepped out of the washroom.
There's a second book, but I don't feel the least compelled to read it; the idea of the authors trying to best themselves makes me cringe.