I honestly think that adults are not supposed to read YA. I don't mean that in a bad way-- it's really fun to read young adult literature. It's just that it's often quite obvious what the author is up to.
This book is a case in point: her first 50 pages are setting the scene as any novelist would do. But Dessen goes the extra mile to make it clear to the reader what kind of high schooler the protagonist is, i.e., her modus operandi regarding guys, what clique she fits into, her personality quirks, why love is something she doesn't understand. Mature fiction (for want of a better word) will often completely skip such banalities, assuming you're going to get it on your own or that figuring that out is integral to understanding the book.
Remy is a hard-bitten, thick-skinned, not altogether nice girl on her way to Stanford, with one more summer to have flings before she does. It's a bit difficult to get past the "not nice" part, even if that girl reminds you of someone you knew during that stage of life (*cough*). Yes, it's realistic, but maybe a bit too far in one direction?
Still, I really like Dessen's writing-- it's breezy and entertaining and forthright and hey, she even does meta themes (Mom's books vs. Remy's life). I've heard her others are quite good, so they go on the list.