I used it today, when I filled my tank it was a bit disconcerting as the water foamed up a fair amount to begin with but as it diluted the water cleared. The dispenser worked fine, but it's hard to believe that 8 small squirts of the solution could effect 800Ls so dramatically.
What I found was that the water wanted to stick to the windows much more so, so if the glass was hydrophilic (water attracting) it would take ages to fall down the glass. It also bubbled up a lot on hydrophilic glass. Hydrophobic glass rinsed slightly better than normal and didn't bubble as much.
The best thing I found was the improved cleaning ability, stuff like birds mess came off a lot faster than normal, I even found that it was removing some creeping Ivey marks off of a window frame that had been there for years.
Down side of the product is getting used to the bubbles, you could waste a lot of water rinsing unnecessarily, but once you get over leaving bubbles on the glass then you should be ok.
I don't think that this product is going to make you a lot faster if you are already doing a good job, maybe slightly, but things like birds mess do come off a lot quicker. I have hot water which speeds me up a fair amount but with this chemical mess that I would normally soak and then come back to came off first time easily, only one stubborn seagull dropping that needed more attention.
I also like some others found that the chemical affected the dead end time of the pump. I don't think it is that the water changes viscosity but rather that the water gets a slight ionic charge that makes it attracted to glass, but also attracted to the hose and hose reel as it is pumped through which in turn creates friction making the pump shut off sooner. Just my theory but I think it's a good one.
All in all I think the benefits so far out weigh the negatives especially considering that it's gonna cost well under a £1 per day even if you have a 1000L tank.
Simon.