For me, Kylo Ren was depicted perfectly and this is where I applaud the creative team that put this movie together. Over the past several decades movie-goers have grown to love the anti-hero. We love the flawed star (i.e. John Mclane from Die Hard always comes to mind). This is a totally different take on that concept in that Kylo Ren is a flawed villain - he is incomplete. I think people forget that during A New Hope, Vader was in his prime as a Jedi. He was far from an apprentice, he was powerful, but he definitely came across as in control. People feared him but not because he was wildly erratic; he was calculating.
Ren is not that. He is still young and he is still an apprentice. Also, he is clearly struggling between the light and dark side up until that key moment on the bridge. He confronted his father, just as Luke did in Empire, but in this case, he faced his father and killed him outright, defenseless, and in cold blood. He is now ready to take the next step and complete his training. J.J. Abrahms and company could have taken the easy way out and made him a carbon copy of Vader in every way. That would have been a mistake. This creates much more tension as you didn't always know how he would react. Also, he clearly worshiped his grandfather; but on the flip side, he obviously was not as far down the path to being the Sith that Vader was. It was evident in the mask that he wore. He even had it distort his voice, but what was great was how vapid and empty it sounded when he spoke. When Vader talked, his voice had a cold menace to it, which was enhanced with the steady breathing sounds. Again, this enforced for me the fact that Kylo worshiped his grandfather to the point that he tried to emulate him in every way, but came up short. Not to say that he wasn't a frightening character, because he was, it was just for different reasons.
Removal of the mask was necessary as far as I was concerned. The one great thing is that Adam Driver was excellent in displaying a range of emotion on screen. For that moment on the bridge with Han, and for the moment with Rey in the forest, you needed his mask to be removed. You needed to see that emotion, and he pulled it off brilliantly.
The flawed villain...I loved it.