I like the fact that you can put a bit of red in the light. I always found the KPW1 light too blue when reading with a very low ambient light level. I can't use the auto night time mode, becuase the light gets way too orange, or I'll have to put my bed time at 3 o'clock or something... but then I can see the color shifting, and I don't like that either.
So, I've chosen to just use the 'Natural Light' slider as a blue-orange adjustment
I have it set so the light is creamy white.
Battery life with my KA1 is now OK. After two days and a bit of reading, it's now at 97% percent after coming off the charger. If it drops 1-2% in 24 hours when not in use, I'm very happy as it will last 50-100 days before it's drained. That would be comparable or possibly even better than my Kindle Paperwhite 1 at the beginning. (Now that one drains faster, but the battery is four years old obviously; but it's still very usable.)