JLU is steadily becoming a better and better show, which this episode proves just too well. The writers of the show so far have done an amazing job mixing together Silver Age and Modern Age elements, the best example here being Diana's Wonder Spin - which is something the fans have been waiting for for a long, long time.
The talk between Diana and J'onn pointed out that J'onn hasn't really been seen in action since JL became JLU - a complaint I know I've heard from far too many people. His leaving was sad, but it made sense. I just hope it means that we see more of him in the future...maybe he'll return with a bigger role?
I'm starting to wonder if maybe Grodd will be looking for more things of mystical origin - like the Spear and the Viking Prince. That should be interesting to find out, and I'm starting to wonder what the story arc of the season is leading up to.