I absolutely loathe Nihlus with a passion. I get the raid is supposed to be challenging, but he is just not fun. I will maybe do 1 fight per day against him, sometimes two or three(usually on auto), but I often just skip him.
As said above, the other two aspects of the raid are in fact challenging, and *fun*. They offer unique, interactive mechanics.
Not only is Nihlus's mechanic not that great(you don't actually do anything. Just sit there n get hit), but you need to time it perfectly, and depending on his speed vs the protecting hero's speed, the whole thing can easily get jacked up and fail.
His whole fight is incredibly frustrating. I won't quit the game, but I freakin hate having to fight him. It's just the worst.