I'd say, in the most flexible terms: It takes me where it meant to
Did the junky romance have me on the edge of my seat, screaming at the villain and tearing up at the corny love confession? Hell yeah!
Did I spend the whole time thinking the villain was a racist stereotype and the romantic interest was a creep? It failed. Maybe it was a great book for somebody else, but it sure wasn't for me.
So let's say instead, the book a complex fantasy story trying to make me engage with a grey character while raising complex issues:
Was I looking for hints to understand the main character, discussing it for hours, and puzzling over the new perspectives it forced me to think about, all while genuinely invested in the outcome? Hell yeah!
Did it condescendingly preach about issues that weren't actually that complicated or well thought out? Or did it instead become an unreadably dense series of names with an inconsistent lead? It failed.
I think writing well is mostly about knowing the experience you want to deliver, then being able to deliver it. Your book will never appeal to the people who didn't want that experience in the first place, but the best authors to me are the ones who know how to get me to set down the book and pace around my kitchen going "OH FUCK OH FUCK I DIDN'T SEE THAT COMING" or "I WAS HOPING, I WANTED THAT TO HAPPEN, BUT I WASN'T SURE" or "I CALLED IT. I KNEW THAT CHARACTER WAS OFF. YOU HEARD ME RIGHT?!" or "THAT WAS THE CUTEST DANG THING THAT'S EVER HAPPENED"
Make me laugh, make me cry, make me unhinged with rage, but, for heaven's sake, do it on purpose.