Enjoyable, but only just alright, on the lower end of three stars. I liked the format, but thought that the book only uses it to minimal effectiveness (most of the "letters" just read exactly like prose as CeCi, Bianca or Rory recount events line-for-line, and it's too easy to forget that it's supposed to be in letter form at all. This isn't how people recount stories to one another.)
There's no new ground covered here; anything in this, you can read done better in the likes of Fables (specifically Fables, actually, as the entire book sort of has a... Sex in the City meets Fables vibe.) It tries to have the emotional resonance of an Into the Woods, but it fails. Terribly. And it doesn't necessarily have to do anything new, but the biggest problem I had was how little I actually cared about the main story. I liked Cinderella's (CeCi) story, because it was the most related to her fairy tale, both the mentality CeCi struggles with, too scared to tell her husband the truth even though he's completely understanding, and also directly in that she's dealing with her stepmother, and her desire to return to cooking, but not as a servant this time.
Bianca's (Snow White) story is sketchier. Who the hell cares about Snow White's father, anyway? I've read the fairy tales, and can't even remember if he's one of the fathers that's just around. The emphasis put on him is so strange and a little off-putting, while her desire to go "off-Page" and live on the Outside ensures that she could basically be any fairy tale story. Her personality has more to do with "she's the ---friend!" than it does her assigned fairy tale.
The same with Rory (Sleeping Beauty). Oh, Rory. You're just a bad person. If Bianca's the Samantha, Rory is the Charlotte, uptight, judgmental, and romantic to the point of actual insanity. Romantic to the point of delusion, because books about fairy tales for adults always have to make optimism cynical.
Rory's story could have been the emotional punch of the book. The fact that she sleeps more and more because she's getting increasingly depressed could have been a perfect way of working her fairy tale into psychological disorders and illnesses. But the fact that the source of her depression is her insane devotion to trying to get her obviously horrendous marriage to work made me want to beat my head against a wall.
It feels shallow, where these issues should feel profound, but they're so mishandled. At one point, CeCi observes that "grief is a selfish thing." No, it's not. I've had a lot of experience with grief, and I've never felt it to be. Must just be you, guys! And they are, they're so self-absorbed.
I'd also be remiss if I don't mention the fact that, despite the princesses visiting Disneyland on the Outside, and laughing over the inaccuracies of the way their stories are being told, the author seems to have only a tentative knowledge of what takes place in the original versions, and to be unsure what version she's using; Sleeping Beauty does seem to be closest to the Disney version. Not that you can really tell, because she avoids actually explaining what happened with Rory. The world building kinda sucks, honestly. It gets overly-complicated and confused, because Griep doesn't generally explain it.
So, I didn't hate the book. A lot of it was really entertaining. Its biggest sin is not living up to its potential. Fun, light fluff, that tries to be more, and fails.