With (1), the time when you talked to the person could be anytime in the past.

With (2), it refers to the recent / present time. It started at one point and just recently stopped.

To end a conversation, you could use either of those and the meaning would be the same.

The only difference is that while 'It was nice...' can also be used to refer to a previous conversation, 'It has been nice..' can only refer to the conversation that you're in the process of concluding. The present perfect continuous ties the statement to the present moment, and can therefore only refer to something which is just finishing or has only just finished.

For example:

Yesterday you had a conversation with Tom:

"You:Blah, blah

Tom: Blah, blah

You: Well, it's been nice talking to you, Tom/ Well, it was nice talking to you, Tom. But my train's leaving in five minutes and ......"

Today, you send an email:

"Hi Tom

It was nice talking to you yesterday. I'm sorry I had to leave so quickly..."

You cannot use 'It has been' in this second situation, because this refers to a conversation that took place in a finished time period.

I hope that helps.

The difference is not huge, but I think rather it is contextual. Literally, in the first one, you had a conversation with someone. The conversation is now over, and you are commenting that you enjoyed it. There is a sense of finality.

In the second one, there is an implicit signal that something is going to continue. That something could either be the conversation itself or the relationship with the other person in general.The sentence standing alone doesn't tell us what. Maybe the conversation is going to continue, or maybe you are about to ask the person out on a date or something.

First, I prefer to talk "with" someone, rather than "to" someone. The "with" is better here because it emphasizes that talking is something you do in a pair rather than by yourself.

On a more subtle level, in certain contexts, I might question the sincerity of the person in 1. Does he really mean that he wants to do it again, or is he just saying that to be polite? On the other hand, there is no mistaking the intention of the speaker in 2 -- this is a direct question! I think native speakers often play with frases like these to either indicate an implied desire for finality or continuity, and to be polite. The finality of the statement in 1 is unusual if the true intention of the speaker is for the relationship to continue.

I'm sure other people will have different feelings about this.

grammatically there is a difference. But as an English speaker, I can tell you that we use them basically the same. I use both just the same.