Joking aside, I agree with this paragraph about how showing Kylo Ren's face was a great move.
Sure, everyone loves a menacing villain and Driver's face definitely does not make him intimidating, with his glorious Jon Snowesque curls. But the point isn't to make him scary in the movie.
We're shown time and time again that he is not -yet- taken very seriously by his peers, especially General Hux who tells him how it is right in his face. No one did that to Vader and lived to tell the tale.
People complain that he was whiny, even in tears at times. And he was, at times. But that's exactly what runs in the Skywalker family.
Anakin was whiny, if terribly portrayed by Christensen, until he was grievously maimed and put into a suit that basically MADE him scary. Luke WAS whiny, until he grew up and became a non-whiny Jedi. Kylo Ren is whiny, and has not gone through the experiences of either Anakin or Luke, though he does get a pretty badass facial scarring at the end of TFA. I'm sure he'll grow up plenty in the next movies.
Keeping the mask on for the whole movie would have made the character a LOT less memorable, but those moments where he is trying to probe Rey's mind with the Force and suddenly feels HER probing his mind, and digging into his weaknesses, that was very well acted with just a widening of his eyes and a twitch of an eyebrow. Hardly the stuff of Oscars, but still far beyond what people give him credit for, and galaxies beyond the acting we got in the prequels.