Kylo Ren very underrated
He can block a lightsaber using his hand: “The weapon went flying into the snow. Unarmed, he raised a hand and utilized the Force to fend off one slashing blow after another"
J.J. Abrams describes Kylo Ren as “an incredible power, an incredible force, and incredible potential
TFA Visual Dictionary says he is an almost unstoppable force: "The darkside flows through Kylo Ren, making him an almost unstoppable force on the field of battle"
These quotes show what kind of condition Kylo was in during his fight against Finn and Rey;
“Stunned by his own action, Kylo Ren fell to this knees. Following through on the act ought to have made him stronger, a part of him believed. Instead, he found himself weakened.” -TFA Novel
“Amid the rising bedlam and confusion, Kylo Ren struggled to stand.” -TFA Novel
The fact he was even able to get up after being shot by Chewie's bowcaster is very impressive. The bowcaster was shown throughout the movie to blow stormtroopers off their feet. Kylo was shot in the GUT and he still went on to beat Finn and almost Rey. At one point, he could have finished her:
"Ren held his lightsaber, poised to strike. 'I could kill you right now. But there is another way.'" -TFA Novelization
If it weren't for his injury, Finn and Rey would be dead.
"It was his deadly lightsaber skills that prevented the return of the Jedi Order" -TFA Visual Dictionary