I love WK. I played as him one time and I just couldn't stop playing as him after that...all what you have to do is to get an Armlet and a HOT and you are at that point where you are almost invincible and can push all the towers you want/kill Roshan by yourself/farm efficiently with your crit chance...etc.
You have a stun ability that slows the hero, a good life steal, nice crits and resurrection ulti. What do you need more?\o/