You can still sign up for it. No ranking system. You get points after each win. The system matches you with whoever is also searching for an opponent. Not that many people are in it. It does not cost anything to have a match.
There should be a system coming that makes fairer matches when PvP goes live for everyone.
Phew. I thought the PvP match I had was well very one sided. Couldn’t defeat not 1 single monster of his and so I knew then that I was at a huge disadvantage. Thanks for confirming that proper match making will be coming soon.