I really love this stuff. I use this product on every tub I refinish. It has cut out virtually all fish eyes problems. I won't spray a tub without it.
This product definitely works as advertised but be aware of a couple things. Use it sparingly, its easy to over-add it.If you use too much the finish will have a greater chance at orange peel results. Pay attention to the instructions! Also, if you are getting fisheyes you possibly aren't being thorough enough with the cleaning/prep. The additive is great for exceptionally filthy tiles and/or excessive silicone issues such as found in motels/hotels but don't become dependent on it.