It is what it is is an idiomatic phrase used to designate the acceptance of a particular and unchangeable state of affairs which simply must be acknowledged as the way that it is, or was, or will be. In all honesty as overused as it is what it is happens to be, usually when people say it is what it is it really is what it is. I mean it is what it is really does apply in most situations that it happens to be what it is.
I’m just sayin’ that people have a tendency to say it is what it is when they really can’t substantiate what it is they are sayin’. I mean I’m just sayin’ I wouldn’t use it is what it is as some profound philosophical way of expressing the way a given situation really is but some people do and that is what it is.
Like it or not it is what it is will be a prominent cliché used in the common vernacular for some time to come and that is what it is you know what I’m sayin’?
And that’s the way it is. Wait a minute didn’t somebody famous say that?