Until I got one, I despised chihuahuas. There's a saying that the staunchest zealot to a cause is the convert, and I've got to say that fits here. I've been won over to the Land of Tiny Dogs, and I can't imagine my home without the little guy.
Their reputation as yippie and nervous and unfriendly might have more to do with the owners who treat them like ornaments. If you treat a dog like a dog, you get a happy well-adjusted dog. If you treat a dog like a toy doll, you get a badly behaved dog (wow, I think I just channeled Cesar Milan). That said, I admit I subject mine to various acts of humiliation, like putting him in Superman costumes and breading him.
Every dog breed has a "job" to do: It's in a border collie's genes to herd, beagles have an overwhelming tracking instinct, and retrievers, well, retrieve. Chihuahuas were bred with one job description: to be adored. Mine is very good at his job.