I'll look into the night mode, but so far I'm not a huge fan of that. My wife uses it on her iPhone, and maybe if I can tell it to make only the slightest of color temperature change, that would be ok. But when I see her yellow phone it just looks so gross to me. It's funny though, because I usually prefer the warmer color spectrum, and only put 2700K bulbs in our house. Anyway, I'll play with it. Thanks for mentioning that too.
Night mode is very much still in beta. It's not there by default; you have to run this "enabler" app, and the "automatic" part doesn't seem to actually work, although you can at least manually toggle it from the quick settings shade button.
As to whether you really want night mode, or f.lux or whatever, it's a personal decision, but once you do start using it, and you then flip it off for whatever reason, the blue light will be absolutely blinding. I have f.lux configured to disable itself whenever Adobe Lightroom is up, since you want to see "real" colors when you're working on photos, but if I accidentally flip to Lightroom and f.lux disables itself, it's really a painful experience.