Many bad reviews complain that it is not a genuine Apple accessory
(which I have not seen, so cannot compare).
Others complain that the lock switch hole is not quite centered,
which is true, but the switch is perfectly accessible on my Verizon 4S.
In fact, give that I operate that switch with a fingernail corner,
I prefer the hole offset.
Beyond that, it helps my fingers avoid confounding the touchscreen
while holding the iPhone and keeps the iPhone front or back from touching
things, when laid down.
My primary aesthetic quibble would be the
mold lines visible in hard plastic at corners,
but I prefer that to the iPhone's metal band that it covers.
For less than $4, I can live with it
and replace it if/when it wears out or breaks.