My guild hit the two World Bosses today. This is the first time I've been in a raid since a few weeks before BC came out.
The thing I missed most was having all those people there, beating on the same target. Things can go wrong in a second, and one boss can kill half your raid in an instant.
On both fights, we killed the boss on our second attempt. I died on the first Earthquake in our first Doomwalker attempt; I didn't realize that the Earthquake could do 8000 dmg to you, or that I could easily stay out of its range. Let's hear it for researching the fight beforehand.
The Kazzak fight was a lot easier, at least to me. I killed him countless times back when he was just a lvl. 60 boss before BC, and they didn't change the fight at all (that I'm aware of) besides upping his damage output and hit points. We wiped once because a bunch of people died (I think someone let their mana go too low) but the second time we only had one death.
Neither boss dropped loot that I could use. Oh well. It was still a lot of fun, and I hope I can get back into raiding some day soon.
I died almost immediately on our first Doomwalker attempt.