They're not impossible. However, the heroics do require things like a smattering more crowd control, more coordination, and definitely more time than Wrath heroics. It's definitely feasible and not too bad when you get a group willing to work together, but boy, has it been a bit harsh for some people.
Interested in the wide world of machinima? We have new movies every weekday here on WoW Moviewatch! Have suggestions for machinima we ought to feature? Toss us an email at firstname.lastname@example.org.