similarity metric to compare 2 sets of 2D points?

Question

I am using a software tool SentiWordNet that can map an English word to a pair of numbers showing how positive and negative the word is. The pair of numbers p and n satisfies the 3 conditions.

1. p ≥ 0
2. n ≥ 0
3. p + n ≤ 1

One can process each word of, say, a movie review and then find out the overall positiveness/negativeness.

I was thinking about whether or not I can find out the similarity of 2 movie reviews to compare the 2 sets of (p, n) points.

Are there any similarity metrics to compare between 2 sets of 2D points.

Any comments are welcome!

Thanks, Patrick