The difference between using present perfect simple and using present perfect continuous is: with present perfect simple the action already ended or is permanent (I have talked with a friend). The talk that you had lasted some time but already ended. While if you use present perfect continuous, the action did not end yet, it is still happening. (I have been talking a friend) the conversation did not end, you were talking with your friend and you are going to talk to him/her again. Depending on the context you may emphasize that you are going to talk to your friend again about the same topic or that you're going to keep talking to that person: (I have been talking with my friend about getting a house. He said I should visit his neighborhood...) You were talking about the topic, and the conversation about the topic did not end. (I have been talking to Robert since last year.) Since last year you were talking with your friend, you're still in contact with him and you will keep talking with him in the future. Hope it helps ;)