Yes honestly! I bought some to be slippers (we have wood floors everywhere and my feet get chilly) but I have been wearing them for a week in doors, plus the usual trips out to garden for use of swings etc and no heel fold overwhatsoever. Infact, they are very robust around the heel area!
Now, I am not suggesting they will be a real replacement for real UGGS (incidentally I have the real thing, really did just get these as slippers) but for those of you who don't want to spend out on the real ones, at just £8! (Yes £8!) these are not bad at all.
There, rave over.