I would love to be able to choose a parson and to be able to see what artists we both like. For example you could choose your new/old friend and see that in your playlists (you can choose which ones to compare) you share 70 songs with Avicii and 40 with Bruce spingsteen. And you share 10 of your top-100 played songs this year. And you discovered Kygo in the same moth at the same year.
The possibilities with this is endless and could really be a conversation thing if done in the right way, to be able to scan someones profile-link with your phone in the club and start chatting about your comparable music.
Come on Spotify, this idea have been up before but is inactive now, do something good with it! :)