Often there is very little difference between the present perfect simple and the present perfect continuous. In many cases, both are equally acceptable.
To emphasize the action, we use the continuous form.
To emphasize the result of the action, we use the simple form.
Look at the difference in these examples.
I've been reading this book for two months but I've only read half of it. It's very difficult to read.
She's been trying to convince him for 20 minutes but she hasn't managed to yet.
They've been talking about this for month and they still haven't found a solution.
When an action is finished and you can see the results, use the continuous form.
The phone bill is enormous. You've been calling your boyfriend in Australia, haven't you?
You're red in the face. Have you been running?
When you use the words 'ever' or 'never', use the simple form.