for the best-friends-are-growing-and-changing-and-also-ditching-each-other-or-being-ditched genre, this book is pretty good. the author is just funny. i haven't read the secret language of girls, which this is a sequel to, so i don't know how it compares. but it stands on its own okay. i'd recommend reading the secret etc first, though, because it probably gives you a clearer understanding of marylin and kate's relationship.
there were two things i thought weren't done very well. one was marylin's abrupt decision to stop being a cheerleader and start being her own person, which seemed a little too glib, quick and easy. also, the boy kate sort of has a crush on- i can't recall his name- comes out seeming kind of like a jerk even though he clearly isn't supposed to be.
other than that- it's really good. i love kate.