Inverting the colors is somewhat acceptable if one just reads plain text pages. However, with true multimedia content (e.g., web pages with inline images), the videos' / images' colors being inverted are really a nuisance.
This is why we jailbreakers stick with our brightness reducer and/or screen backlight temperature setter tweakers. They're much better than Apple's color inverter.
Note that I didn't mention f.lux as a screen dimmer utility. Nevertheless, while I do know it screws up the temperature in that for example blues become either black or green, you can quickly disable it when you plan to, say, view some videos or photos, where the original screen temp. should be preferred. I do this all the time. The best of the two words: very easy on my eyes while, say, browsing the web and still the right color temp. when I decide to browse some images. All this some 2 taps + one home button away (maximizing the window of f.lux and tapping the en/disable button + exiting the app).