i just finished a Psychology degree and before I started it I really liked Malcolm Gladwell and thought he was spot on, but to be honest a lot of the pop Psych I personally find unconvincing. It's kind of like they've been made to dine out on. They're interesting but I don't think very scientific. Do still quite like them though I guess.
Just while I'm commenting, OP my favourite nonfiction book I've read recently was Guns, Germs & Steel - but I think it might suffer from the same sort of thing I was just talking about.