I realize some of you uber people have probably been doing heroic dungeons for months, but Kaliope just got her first key a couple of weeks ago. Plus she's been trying to get through all the Karazhan pre-requisite quests, so I hadn't had a good opportunity to try a heroic instance yet. But last night I not only got my key frag from the Black Morass thanks to a great guild group (TY-Oldone, Dirtybirdy, Badmonkey & Squeekie!), I also got a stab at my first Heroic run.
We ended up going to Coilfang since there were more people with that particular key. They chose Slave Pens, which was fine by me since this was my first time out. As a healer, I wasn't interested in biting off more than I could chew <heh>. Still, I was bracing for the worst. I put on all my best +heal gear, popped a +heal pot and ate some +heal food. Our leader warned us up front that we could not afford any mistakes with aggro, and he was definitely right about that. That's probably the biggest issue I noted, if anyone steals aggro from the tank they will die. No room for error on that one unless you are fan of wipes and repair bills.
Another potentially major problem is that keeping the tank alive requires almost chain-healing from the healer. This means that other folks need to avoid being hit or bandage themselves. That's not to say there weren't random moments that I couldn't HoT someone, but certainly not enough to be counted on. My feeling was that basically every pull was akin to a normal "boss" fight in terms of diligence to aggro issues and conservation of the healer's attention.
If you have yet to attempt this, maybe my experience will help you out. Overall it wasn't as horrible as I'd anticipated, but definitely not for the sloppy or faint of heart.