Nice deep blue water
If you follow the directions exactly this turns the water a beautiful color blue. It doesn't really look like the stock pictures, which is a good thing. The blue really just makes it a nice deep blue without looking too fake. Our liner is white so we use this for pool parties to make the water a nicer color.
Be very careful when dumping into the pool. The first time we used this the wind splashed a little bit of the mixture onto the the edge of the pool while we were dumping it in the water. It dyed the white edge instantly and we haven't found any way to get it off yet. When applied directly into the water the correct way, nothing gets dyed - only the water.
One bottle is enough to dye our pool twice (in-ground 18'x32' plus steps area with 9' deep at the deep end). It takes a couple days to fully circulate out of our pool with the pump running 24/7. Once the water returns to normal color, you'll probably want to backwash the filter to get the dye out that gets stuck in there.
I can't speak for the other colors this comes in. We have only used the blue.