It's a coin flip, like any insurance. Geography plays a big part, but its still a crap shoot.
I'm in NY and have it on my Mercedes and in 2 years, I've had to replace 4 AMG rims and two tires, which would have cost me around $4000! I'll take my $1000 insurance over that.
That said, I had the insurance on my Audi S5 and had two bent rims that shook the steering wheel pretty bad and they wouldn't replace them, since they still held air.
So obviously I'm happy I have it now and was pissed I did on the s5...
On BMW's, it wasn't offered on my '99 e46 and I bent 3 of them, but back then it was cheap and easy to replace with reconditioned wheels. I wasn't offered it (though it did exist) on my '07 x5 4.8 with the 20" wheels and I drove it from NY to Baltimore and back (over the George Washington bridge and it's battery of potholes) and never bent a single one.
I opted not to get it on my wife's x3 because the tires (28i with the 18" wheels) aren't quite as low profile. On my next car (F30 335 sportline with 19's), I will probably take it.
In places with better maintained roads (don't get me started on how much I pay in taxes and how many potholes I get for my money), I would probably skip it.