Personally I think they're great, it's one of my pet hates in almost all cars that the time your windscreen is most likely to be steamed up is when the car has been parked up overnight and it's cold outside, and that's the one time the heater is completely useless. I don't care so much about frost/ice, I'm quite willing to clear all the windows with a scraper, it's the condensation on the inside I hate. I refuse to wipe it with a cloth as it always leaves smears that are impossible to remove until the window is completely dry again. So I have to sit and wait for 10 minutes with the engine idling until the heater is warm enough to demist it... ah the wonders of modern technology

I'm amazed there hasn't been some other technology developed to solve this issue, I remember back when I was a kid and long before I was old enough to drive (think it was 1991) my dad had a Ford that had a quickclear windscreen. 17 years later (god I'm getting old) and we're still sitting in brand new cars idling our engines to demist the windscreen using the heat from the engine

Got one of those on my Sapphire Cosworth , hate it, especially at night with on-coming headlights, they really shows up at night and do your eyes in, especially at high speed which is something you really don't need when your trying to read the road!
Daytime not too bad until you switch it on, distorts the vision until it’s fully warmed up.
Chris.
I've never owned a car with one, but I have driven a few, and I found I quickly got used to it and after a while my brain just filters out the extra glare so I don't notice it. It would be nice if it were possible to have the same functionality without the wires being visible though.
On the latter point, I notice a similar thing on the rear window of my BMW. It has a very similar setup to the quickclear for the rear window heater, lots of very thin wires laminated between two layers of glass. Only difference is the wires are straight instead of wavy, and a few wires are used for the aerial so don't heat up. Normally you can't see them in the mirror, but after it's been switched on for a while you can see some distortion. It actually serves as a reminder to switch it off, but I've no idea why it does that as it's still visible after the glass has completely cleared
Oh and I've no idea why they decided to use such a system on the rear window... it costs £800 for a replacement should you need one :-/