Well, I've had mine since about December: I don't fall over as much as I used to and the outer side of the heel has barely rubbed away at all (I would usually have to get 'normal' shoes re-heeled after a couple of months to help prevent aforementioned falling over).
I find them quite comfy (they're actually about the only shoes I can really wear at this point, but I'm an exceptional case), and you can amuse yourself (and others) by rocking backwards and forwards at bus stops.
They're fairly pricey, so in typical fashion there's already a cheap imitation available in the form of
Fit Flops, but I'm a bit wary of such 'bargains' and anyway, it would be difficult to wear my sparkly fairy socks with them and my feet would get cold.