I love the stuff, but on the heavier dirt and screens with cobwebs I still have to wipe the screens after I spray them. But the coloring is what it's all about... nothing else gets them back to the fresh black, wet looking shine.
If you buy it in the bigger quantities it's still expensive but easier to stomach. My biggest complaint isn't the price, it's how long it takes to get here. It's taken just shy of 2 weeks both times I've ordered... I'm used to WCR getting stuff here in a few days tops, but this stuff ships straight from the manufacturer and it's ssllooww.
Also I found that the garden sprayer wasted too much solution. The regular spray bottle works much better imho. It wears out your fingers though, heh