My friends Vdub Jetta GLI has them, lots of sidewall flex, grip decent for the most part though. Not exactly a great performance tire, but fine for the street.
I have ZRI's on my car. I'm no tire expert but here is what i've noticed:
1) Don't even think about driving on any amount of snow/ice, im talking like even the TINEST patch of it. I made it through a whole winter with bald tires all around and was fine for the most part. Put the ZRI's on last fall and i got stuck in my driveway the first snowfall. Sandbagged it up and still had no traction, got stuck 2 more times trying to get the thing to go anywhere on ice and finally gave up and bought a winter beater.
2) The traction, from what I can tell, isn't that great. In my bone stock 96 GT auto i can somehow spin the tires without any smoke or squeal/chirip/anything. Usually you'd think if they spin and then get traction they'd chrip or something, not with these...as far as i can tell or remember.
Overall if you're looking for a top of the line performance tire or a tire that'll be for all seasons, these aren't what you want. If you want just a decent looking tire that will get you from point a to point b fine, from what i've experienced in my 8 months of having them on they've been fine.