I feel like I'm really behind. I fought Murmur for the first time last weekend. We dropped him on our first try. I got the first piece of my Karazhan key.

He's kinda cool looking (though I've seen Ragnaros and Thunderaan before), and the "sound wave" visual effects are neat, but what really impressed me were all the different sound effects in the fight. They were completely unlike anything else in the game, and they were also somewhat disorienting (which I thought was really cool). Lots of weird squeals and stuff.