My guild decided to start on normal. Despite the server's best efforts, we cleared it and then got 1 pull (43%) on heroic Nythendra before raid time was up. I was tanking on my 851 DH, and thought I'd share my thoughts and observations to see how they match up with everyone else's.
First off, I was really happy with my mobility. It was great for jumping in and out for various mechanics, picking up adds, etc. I was a Blood DK in WoD, and the difference here was night and day. Obviously Blood can still do the mechanics, it was just so much easier and more fun on my DH.
Secondly, I was pretty happy with my AOE damage. The healing it gives is nice too, not only for the healing itself but for drawing threat on an add that didn't get hit by the brunt of it, or took a large single target nuke from a DPS'er for some reason. I'm mainly thinking of accidental egg sack pops on Elerethe here, but there were [probably] other instances too.
One thing that made me nervous was the amount of incoming damage. Even on normal, there were a few instances where I was really relying on my healers even though I had DS up. Maybe that's just the new tanking model in action, I'm not sure. Anecdotally, my Prot Warrior co-tank didn't seem to periodically dip like I did despite being 6 ilvls lower, though I'll have to check the logs later to see if that's what actually happened or just my perception.
Overall, last night left me feeling pretty good about my class choice. How did everyone else fair?