Oh, I'm not exactly worried, more intrigued and curious than anything else. Being from Spain's capital (Madrid) I think I've got the basics of big cities with over a million people pretty well learnt already. I'm speaking more of relevant local information, such as absolute must sees, should not go places, public transportation tips (as I most surely will have no car with me), nice stuff that usually doesn't make its way to tourist guides, spots relatively close by worth visiting at weekends... Those sort of things.