I really like it a lot! Raiding feels like a challenge again!
I couldn't find much info on the heroic bosses but I used Heroic Trial of the Crusader Encounters as reference on what abilities there are to look out for. Rather than me describing them all over I recommend looking through that article.
My first thought on Gormok the Impaler was "-Are you serious?". He hit the tanks hard. We had a couple of tank deaths on him but on our third or fourth try we made it to the worms and then died from some poison confusion. We got to Icehowl on the fifth try total I think and one-shot him.
Jaraxxus took maybe 3-5 tries and here you want to kill the portals and volcanoes or they will just keep spawning adds and you'll be overrun.
I think we got the champions on the second or third try but don't ask me how :) It was a clean kill though. I didn't really notice any new abilities or effects, just that they hurt more.
Then we sort of got into trouble with the Twins so they are still alive. We're down to just above 30 attemps left on our tribute run with Twins and Anub'arak still standing. It should be doable!
On another note, I'm really enjoying leveling my Death Knight who is level 64 for the moment. I just read up on talents, rotations and glyphs so I feel like I know what I'm doing. I went with the Unholy tree as that's the tree I enjoyed the most when I ran him through the starting zone so long ago without really knowing the class well. I took him through the Plaguelands back then for some questing but once he got to Stormwind he got stuck in the AH making money. My intention was to reach level 65 so I could learn the Northrend glyphs but I think I'm surprised at how fun he is to play so I'm very likely to keep leveling him when I have the time.
Here's some grinding music to enjoy!
The Crystal Method - Smile
The Crystal Method feat Matisyahu - Drown in the now