You use "has been" to describe a situation that started in the past and continued until now. The situation can be something that happens continuously:

They've been arguing with each other.

She's only been gone one day.

Or it can be an action that is repeated over and over for a length of time:

I've been going to that grocery store for over 25 years.

The phrase "It's been" is used to describe your general recent situation. It's like saying "my life has been ___":

It's been tough looking for a job in this economy.

It's been a fun vacation, but honestly I'm ready to get back to my routine.

Or you can use "it's been ___" to talk about some object. For example, if the coffee machine at your office doesn't work, you can describe it like this:

It's been broken for a few days.