I have considered using one. I've been reading up on more threads than I can keep track of, but there seem to be more divergent opinions on coatings than there are on polishers... Besides, I wanted to get the car to a high level first, and if there are mistakes - I didn't want to 'lock' them in with a coating. I'm a bit annoyed that OC and CQuartz both have lines that non-pros cannot buy (if it's because of the difficulty of applying the coatings, then they should offer paid instructional hands on courses and then let people who attend these training courses buy the stuff... sheesh... marketing 101...). So, I have to look at the 'non' pro coatings and go from there.
I've looked at the OC regular, Cquartz regular (both for us peons), the Polish Angel line, and Gtechniq. Ease of use will be high on the list (which will likely strike out the first two) and protecting is second on the list of importance. I'd really like that in addition to hydrophobic properties, that the coating also have anti-static properties so that pollen and dust doesn't get attracted to and stick to the car...
I'm still amazed at how fast the car got covered in dust from the cedar trees today...