Kylo is kinda cool. First I didn't like him too much but the more I think about him the more I like what they did with him in Ep7 and Ep8
The main problem I see with Kylo is that he has essentially already lost twice to Rey. So unless there is a shift in power, he doesn't seem like a threatening enough villain. Rey doesn't need to build up to defeat a seemingly unstoppable villain, she has already done it twice.
I don't understand what is going on but I was waiting for a British imitation of the Brazilian "GOOOAAAALL!"
Well the first time was against a severely wounded Kylo (emotionally and physically, he had killed his father and had been shot by Chewie) and he still had the upper hand during most of that fight. He also got stronger in the meantime. The second fight was also pretty even and he didn't really want to kill her for parts of that fight IIRC. They seemed pretty evenly strong to me. I also think that's what the movie wanted to imply, based on Luke's assessment of their powers and them ripping the Lightsaber in half. So there is a development of Kylo, and he is getting stronger. That is threatening enough for me.