Very.
The iPad Air has really shaken my confidence in Apple. Maybe it's iOS7, maybe it's the 1gb of ram, I don't know and I don't care. All I know is the crashing and constant reloading is awful. I regret upgrading from my iPad 3.
Between this and the 5s' fingerprint scanner I'm not sure Apple's "it just works" mantra still means anything.
If it were happening to the majority as I stated perhaps elsewhere, there would have been a slew of returns. Since that wasn't the case, then the question is why weren't these devices created equally OR what have folks done to muddy the waters?
I spent last night trying to get my Air to crash or refresh. NADA!!