Are Cataclysm heroics too hard?
Are they harder than heroics at the end of Wraith? Heck yes. We don't over-gear them.
Are they harder than heroics at the beginning of Wraith? Yes, I believe so. I don't remember group makeup being important (besides the obvious healer/tank/3 dps thing), and I don't remember CCing.
Are they harder than BC heroics? Not sure, since I never ran them at level.
But there's several other things going on here that make difficulty harder to judge.
First, we've all been revamped. This hit some classes and specs harder than others, and we didn't have much time to get used to the new status quo before Cat.
Second, Blizz has decided to change the way we heal with Cat.
Third, we have far less control about who we end up grouped with (if pugging) and far less knowledge about them.
Fourth, CC/interrupts/stuns/kiting hasn't been needed for pretty much all of Wraith (unless you PVP), so most people are anywhere from a little rusty to completely unfamiliar with them.
Honestly, if we were coming into Wraith heroics this way, I suspect we'd find them pretty difficult as well.
But I think the better question to ask is "Are Cataclysm heroics fun?" Well, not for me thus far. Running with my guild makes them more entertaining, but I still haven't enjoyed one yet. I do them because I need gear to raid, not because I want to.
The unforgiving group makeup problem is really the deal breaker for me. A suboptimal group makeup, even if everyone in the group is a great player, makes for lots of wipes and frustration. Don't have enough stuns or cc? Then certain trash pulls are nightmares, nightmares that reoccur over and over again. Call me a wimp, but I really don't enjoy that sort of thing. Most of the boss fights I've gotten to see I thought were great (except for the tornado boss since that's a little too RNG dependent), but the trash, ugh.
So for me, I think the answer is that, yeah, they are. They're too difficult for me to have fun in them, and I have to wonder why, with Blizz introducing the random dungeon finder to make it easier to run stuff, that they went to such a difficulty level. Seems counterproductive to have this tool to make finding dungeon runs easier, and then bring out a bunch of heroics that discourage pugging due to group makeup and difficulty level.