Brewfest is definitely the best holiday in the game. Or it was, before much of it broke. But it will be again next year, when they (hopefully) fix everything.
The Dark Iron Invasions were really fun while they lasted. If you missed them, here's what happened: dozens of huge drilling machines would pop up in the middle of the Fest, and several Dark Iron dwarves would pop out. You'd wave to one of the barkers, and they'd throw you a drink. You would drink the drink, and auto-throw the empty mug at a dwarf, which would get you a ticket each time. The problem was that people didn't know how to activate this, and they just spammed /wave, which apparently caused lots of lag. So they had to disable that event, which happened hourly.
Fortunately, the ram-racing quests were still there. The two in the game were distinctly different from each other, and were completely unlike anything else in the game. They're a lot of fun, but I'm glad that mounts don't handle like that normally.
I've got my mount, and I'm going to work on getting a hat and maybe some of the other items if I have the time.