I wasn’t too fond of the male narrator for this one, and I think it lessened my enjoyment. I also felt the age gap was a little too much with Linnea being super young. I didn’t buy into their relationship by the end like I was hoping. 
If they had been older by a few years, I would have felt they were more on the same page. But with Linnea being 22, fresh out of college, AND naive/sheltered/shy, it was a somewhat unbelievable connection. The start of their physical relationship when no one knew about them, with Charlotte home and in the next bedroom, was eyebrow raising and strange. Waiting until she was at a sleepover would have been way more realistic.
The way Caleb was portrayed was a little creepy (always focused on his appreciation of her body; I wanted more of an emotional connection between them). I didn’t feel that way about his character in the first two books.