I was part of a guild group, which obviously changed the level and character of interaction. We were all on vent, which helped significantly with communication. Since we knew each other, there was a level of civility, discussion and co-operation that you only rarely experience in a dungeon finder PuG. The trash was tough, use of CC was liberal - I actually had to be told it was OK to do a sheep pull! - and we wiped more than once. We actually started with the Stonecore, wiped several times on the first boss, and eventually re-queued and completed the Halls of Origination.
Overall, it didn't feel like we were running dungeons, even heroic dungeons. I'm essentially a Wrath player, having barely hit Outland on my first character when Wrath was released. So my experience with heroics is limited to what few I ran at level in BC content, and what I saw in Wrath. Even in those limited instances, 5-man content felt like 5-man content. Tough, definitely, but not horribly impossible.
Stonecore and Halls of Origination were... roughly about the same level of difficulty, I'd say. Less trash than the BC instances, but what trash there was, was tougher. More like a collection of mini-bosses than elites. The bosses themselves were more active than Wrath bosses. To me, it felt like there was less tank-and-spank, more special abilities, more decisions to make and more opportunities to react instead of following a pre-planned script.
So, yeah. It felt less like a heroic, and more like a 5-man raid.
I like it.
Leveling through the new Cataclysm content, there are a bunch of quests that are obviously designed to help teach people how to react to, and deal with, the kinds of special abilities you find in heroic and raid bosses. Fire to move out of, positioning requirements, stop dps and shield... that sort of thing. All good.
Heroics feel like the next step in the chain, where you start having to do additional work. Things like crowd-control. A lot of the HoO fights seemed to involve managing adds as well. Quite a few had me switching targets based on the flow of the fight, or from single-target dps to aoe and back based on what was happening.
I won't lie - it was rough in spots. I died a lot. My dps wasn't near what it could have been or should have been, and I let my sheep expire a couple of times when I shouldn't have. But you know what?
Next time, I'll be a bit better than I was this last run.
Next time, I'll have learned a bit, and be ready to switch targets when the fight demands it.
Next time, I'll know when to ice block through that aoe effect to save the healer a bit o' mana.
It's not just re-learning skills I already had, though. It's learning how to adapt, how to make the right decision to use the skills and abilities I have to their best effect.
Sure, at some point, even Cata heroics will be trivialized by folks running them in top-tier gear. I have a suspicion, though, that that time is far in the future... and that even then, competent players with good coordination will still do better than the overgeared "gogogo" crowd.
As 5-man heroics, Cata dungeons are hard. As raid trainers, though... they're excellent.