Truetone is not just blue to yellow. When they originally explained it on the 9.7" iPad Pro, it was using paper as an example. Showing the difference of various atmospheric lighting conditions, the tone and lighting of the screen would reflect that much the same way it would reflect off paper. If I am in a room with a lot of plants, the hue would ever so slightly change to the green, when using it for awhile you hardly notice it is activated. I didn't think I would like it on the 9.7 and I ended up keeping it activated and loved it. Your mileage may vary.
But here is the good news......if you don't like it, you can turn it off, and Apple made that button so easy to find and use
But here is the good news......if you don't like it, you can turn it off, and Apple made that button so easy to find and use