Not much to say about it. I spent about 45 minutes running about in the Dalaran sewers, was killed several times as guards took a break. I believe it took 3-4 Treasure Goblin spawns before I was able to click a portal. Ended up in a field with what seemed more people flagged for PvP than cows. The Cow King was sub 10%, a couple of spell casts, looted the body got my achievement and I hearthed out. Only to get ported back to the point I entered the portal a few minutes later.
I spent more time in guild chat explaining how to get the portal than actually doing the thing, including explaining you could only loot him once a day.
It’s great they included it in the game vs having to go play Diablo to get some thing in WoW. But communication of the event gets a thumbs down from me. Some one may eventually realize. Not everyone reads WoWhead or gaming sites for news. Some people just want to log in and play. It would have been wonderful for Dekard Cain to show up in the major capital, or to get a letter in game alerting us to the event.
I know there is a fancy town portal tome to collect, but once I help one or two others get the guitar? I’m putting this down as a one and done.