I left a comment on the io9.com article about it that was written in opposition to the Slate editorial. I said:
"I was a YA librarian for 8 years. And for those 8 years, part of my job was to read and review and booktalk books geared toward a teen audience. Some of my favorite books are among those YA novels.
It's not just a marketing term. It's also irrelevant. People should read what they want to read. It doesn't matter what age level the books are written for or marketed to. The Harry Potter series is a children's series, yet people from 6 or 7 to 100 or so read them. Superhero comics have traditionally been marketed to boys but that didn't stop me from reading them, starting in 1960. I read adult books when I was a kid, adult and kid books in my teens, and as an adult, I read every age level book I want. One of the best books I've ever read was a children's book: Holes by Louis Sachar. I read it as a middle-aged adult. Other than authors and publishers wanting people to read their books, no one should care what other people are reading. As a retired librarian, I'm just happy people are reading."I really was bothered by the author of the article defending adults reading YA novels by calling YA lit a marketing term. Which it is, of course, along with genre labels and even the decision to dispense with genre labels when they think an author can break out to a wider audience. But YA novels are written in a certain way. They focus on teen characters, with strong pov that keeps the focus on the particular issues teens deal with, like puberty and acceptance, even while dealing with the larger realm they live in. Sometimes, it's the conflict of trying to be an adult as their realm requires vs their struggle to mature, deal with hormones, and so on. You'd be more likely to find adults eager to read about characters ranging from childhood to old age. Teens are more likely to want to read about characters their age and a few years older. It's the rare YA novel that would be focused on an 80-year-old. Or an 8-year-old.
YA novels tend to not have digressions into rhetoric or authorial editorializing. And since they cover readers from 12 through 19, they vary in their vocabulary. They also don't feel the need to toss in an obligatory sex scene, though they might cover sexual experiences. I'd say they tend to be shorter than adult literature, but there are so many exceptions these days, starting with the Harry Potter books, which were written for children, covering a lot of YA fantasy and science fiction. One reason I love YA fiction is how, when good, it tends to get to the heart of a story and not meander. Character development tends to be strong and the writing clear.
Bottom line: read what you want. And don't let anyone make you feel bad about it.