I really don't know if Vader's much better though. When Ren has a tantrum, he damages property. When Vader gets mad, he
kills his own officers! 
When Ren gets mad, they send in a repair crew. When Vader gets angry, they send in the coroner.
One of my favourite abilities in the Star Wars Miniatures game is this Commander Effect from
Darth Vader, Dark Jedi:
Whenever an allied character without a Force rating gets a natural 1 on any roll, that character is defeated and all other allies without a Force rating get a +2 Attack. (These bonuses stack)
So what this means is that if any non Force-user on Vader's team rolls a 1 on a 20 sided die roll (which means a critical failure), Vader
kills that character, which then scares the Poodoo out of the rest of the team who all fight harder (hence the +2 to Attack) because they don't want to be next! And if another character rolls a 1, they also get killed and everyone else gets another +2 to Attack (hence it becomes a +4, +6, +8 etc.). Every time I played a squad with
Darth Vader, Dark Jedi in it and I'd roll a 1, I would put on my Vader voice and say,
"You have failed me for the last time," and make choking noises as I removed that defeated piece off the map!
Vader seemed able to draw strength from his rage, whereas it might be more of a liability for Ren. But this may further serve to demonstrate that Ren's (attempted) conversion to the Dark Side hasn't been nearly as comprehensive as Vader's. He's arguably more of a wannabe Sith.