When reading at night on the Aura HD with the light on, it's about 8%. The other night, I tried to set it to 100% to see the difference. Wow, that was bright! And too harsh for my eyes.

I had to set it lower than 10% as fast as possible.
I don't have a tablet, but I check emails and tweets on my smartphone. Even at the lowest setting it's definitely not as comfortable as reading on the Aura HD.