Quote Originally Posted by chaika
this is giving me the creeps.
it is giving me the creeps.

You pick the pronoun to use just as you would ordinarily decide which to use in any other sentence. Maybe not - since "it" seems to indicate a referent more specifically. I mean, if you and someone were walking around in a haunted house, you would say This is giving me the creeps - "this" meaning the whole event. But you could also say I don't like this place, got a bad feeling. It's giving me the creeps. "it" refers to "place". HTH
So this = all this and it = this particular thing, right?