I've been using it, but can't say for sure if it has improved coral coloration. My corals have improved in coloration, but I have also been focusing more on tank husbandry in general in that timeframe. If I had to guess, I'd say that Trace Colors is more essential in tanks with a lot of corals and very few/nonexistent water changes. There are lots of tanks out there that don't do trace element dosing and have really amazing colors with just regular water changes alone.
One word of caution: when dosing Trace Colors, make sure to dose into your sump, the back compartment if you have an AIO, or by mixing into a cup of tank water first and slowly adding into the flow of a powerhead. I'd heard stories about dosing directly into the tank and too high a concentration dripped on corals and causing STN, but stupidly ignored them. The first time I dosed, I used the dropper directly in my display and a pink acro right underneath the the dropper STN'd within 12 hours. What I've been doing these days to remedy that is dosing trace colors into my weekly water change water.