One thing I appreciate is that the series doesn't attempt to drag one secret out for the entire gazillion books. In the beginning of the second Pretty Little Liars book, you find out the big deal from book one.
I didn't enjoyed the first book thoroughly, but wasn't bothered by its being "objectively terrible." In Flawless, the book and series' repetitive nature becomes harder to ignore, and you find yourself really wishing the girls would just cop to their shit and take seriously the idea that A could actually be Ali already. Plus, boy, do they make poor choices about their academic and romantic lives, and sheesh are their families unbelievably unsympathetic! Even so, it's possible I just downloaded the third...