I've seen a few "nerf heroics plx" threads lately on these forums, and one of the main arguments of nerfing them, is that the main player base, popularily called casuals, would eventually quit in frustration.
I disagree. Most of the "casuals" raided in Wrath, and honestly, if you want to raid in Cataclysm, you need the practice of heroics. Me and 8 of my irl friends plus 1 random rogue went to Blackrock Descent last night, and HOLY CRAP, it was hard.
We pretty much steamroll heroics, and we spent about 3 hours wiping on the first boss. Granted, we weren't fully enchanted and gemmed because gemming enchanting blue gear feels a bit "meh", but we bit the sour apple and did it anyway, just because we had to.
So we finally downed him, but all I can say it's that it has very little room for failure. If you take uncessary damage that you should have avoided, your healers will go oom pretty fast. We went with 3 healers, our ret pala threw in heals as often as he could as well.
We haven't tried any of the other raids yet, but it most likely won't be any easier.
Honestly though, it was super challenging and super hard, way harder then most of the ICC heroics, and it feels great.
Just think about this before whining over heroics. Yeah, they are a massive pain with PUG's atm, but they all have to learn to improve some how IF they want to raid in Cataclysm.