From a business perspective, Gloss Coat is an awesome choice for someone who wants a very simple way to introduce their customers to a ceramic coating. It happened to be my route, and it a great entry to them.
For the enthusiast, or "enthusi-pro" it might not deliver the water behavior or percieved longevity they like upon initial interaction.
I added CarPro Gliss, Lite, and CQUK 3.0 (also have SIC but haven't played with it yet) to my offerings, but as things are beginning to shift focus (from pursuing actual detailing to local product sales) I'm considering going back to just offering Gloss Coat. I keeps my detailing operation tight and minimalist so I can spend time on the other endeavors.
I have noticed that the more I work with Gloss Coat, the better my results are. Because the application is so ambiguous to me I have to "trial and error" my usage of it. Vehicles I did early on seemed to do well with, but I did my gf's old truck, my car, and a co worker's car, and like you I wasn't as impressed - although it was better than a single layer of CarPro Lite and UK - which may change should I run then through the same trial and error I am with GC. I re-did my co worker's car and it turned out great! He beats the daylights out if it, runs it through the tunnel wash on occasion, and goes long times between washes. This will allow me to get a good observation of what to it can do with my latest application method.
I just polished my hood with 3D ONE, hit it with Optimum Paint Prep, and laid down some Gloss Coat. And hour later I applied Opti-Seal. That night it rained, and I got some pretty killer water behavior.
I did find a high spot on my gf's Jeep, and I have had the tips clog up on me with Gloss Coat, so I know it does something, but you have to decide for yourself. On the driver's side of her Jeep I did two layers of CQUK3.0 and one layer of Gliss. I have to admit that it's pretty awesome! Very slick, very easy to clean, looks and feels like a good chunk of coating is on the paint.
I may try the Gyeon coatings too because I'm not a big fan of double layers. Takes too long, too much to worry about, too much waste in applicators and towels, really harsh chemical fumes etc, etc... Actually all that makes me want to stay with GC even more...
Like Mike Phillips says, find what you like and use it often.