Not sure if this counts as YA, but I'm reading LUCKIEST GIRL ALIVE (which alternates between the MC at 28 and the MC at 14). It's gotten some very polarized reviews on Goodreads, so I'm curious to see how it pans out. I'm really enjoying the writing, but the MC is...a bit difficult .
I read LUCKIEST GIRL ALIVE earlier this year, and thought it did what it set out to do pretty well. I wasn't expecting it to get as dark as it did, though. I agree with Fuschia that the adult MC's development/change is key. If you can handle the character long enough to make it to the end of the book, you might find her arc satisfying!
I am about a hundred pages from the end of THE 5th WAVE right now, and just trying to finish it before the person I borrowed it from starts banging on my door demanding it back. I am more interested in Cassie's storyline than those of the other characters; I plan to at least finish the book, but I don't know if I'll continue with the rest of the series (which is probably a good thing for my relationship with the person who is lending them to me, tbh).