Im a frequent visitor over there and most of my stuff is Adam's. They do make quality stuff and a lot of it is easy to use. I have noticed as time goes on, their products have been getting better. They are a small company which dictates their higher prices. Another thing I want to point out though, is their shipping prices are pretty reasonable compared to others.
I personally believe that not one car care product line has the best of everything and I am venturing out and have tried new things (i.e. PERL, UWW+, DG 901, 281 etc.) and will continue to.
The comment about how a PC won't finish well on a black car, id really like to see it because I have never read that one before from Adam's or any place else. It's funny how people bash other companies without any experience from them and/or not getting the whole story.
One thing is certain IME they do have one of the best customer service in the business and will back you up 110% with their 110% guarantee. What other car care company's CEO will call you after hours to thank you for your business & asking feedback on their products from making their first order with them? I actually recall a while back where they had a disgruntled customer that didn't know how to polish a car and Adam's offered to send someone out to him to show him how to do it.
With that said, sometimes it may not be all about products for some people. It may be about their experience/customer service community etc. That's why Adam's has such a loyal gathering.