My roommate has a pug and he's cute and fun (and a little overweight) when he's around us but goes crazy when it comes to just about anything else. He can't be around my husky, or any other dog for that matter, because he'll just start a fight that he will lose.
I just feel like they're another breed that is prone to that cocky mentality that Chihuahuas are so famous for. A friend of mine had a pretty docile one though, so I guess objectively they're cute. I prefer big dogs though.