The first problem is, I don’t really remember what happened in the last Cinderella book. And, now that I’ve read my review, I understand why.
So, here’s the deal. Cinderella is a spy, the kind of actual spy who her own people don’t know is a spy unless they’re her bosses, because need to know and actual effectiveness and all that. What she is not, I suppose by virtue of being under the purview of a different author, is the kind of character who is allowed to make lasting impressions on the main plots of the Fables series from the safety of her side books.
Therefore, if you like Cindy as a spy character on her own merits (and I have decided that I do), these books are fun, if ultimately meaningless, fluff. (With occasional clever visual cues that riff off the not as clever title cues that these are James Bond inspired.) If you do not, they are thusfar devoid of any content that you will feel bad about missing. Which is a pity, but only because I do like her on her own merits.
 In Fables Are Forever, her historical and modern competition (spy vs. spy style) with Dorothy Gale is revealed and explored in what I think is fair to say is a surprising degree of detail.
 Actual review in the footnotes. This is a new low.
 Willingham is only here because they reprinted issue 51 of Fables in the collection, which it seems was Cindy’s first spy appearance, and which I seem to have mentioned at the time? (Or at least near the time.) So that’s cool.