The 303 works well enough, but the aggitation is key. If you just spray and blot/extract, it won't give you as good results. Make sure you don't get it on paint. It tends to leave a residue or marking on it. I tried it on some metal next to the carpet I was working on and it left marks in the exact pattern of the spray. Wouldn't come off after rinsing repeatedly. Did polish off, though. I should mention that it doesn't say for use on metals on the bottle.
Also, I've read that the 303 aerospace cleaner is the same stuff, just more concentrated, so you can dillute it 30 to 1 and get the carpet cleaner. I haven't tried this one yet, but this bottle does warn not to let product dry on surface.
Some other good point on the 303 spot cleaner were the nozzle had a foam option, chemical is biodegradeable, non-toxic, and non-flammable.
One bad thing is the tube is a bit short. You can't get the last bit out if you're sqirting down at an angle (I would expect this to be the most common direction for a carpet cleaner).
Overall, a good product.