For about the first 2 days, I thought the text was too small on my 11" Air, especially when reading in Safari. The solution for me was to change the minimum font size in the Advanced Safari Preferences.
As a general comment, flux is much better when you can approximate the ambient light in the room. If you are using bright white LEDs (which tend to be bluer) or cool-spectrum CFL, the yellow-ness of the screen can be very off-putting. However, if you have warmer-spectrum lighting (incandescent, halogen, tungsten, warm-spectrum CFL) or complete darkness, the effect is much better. Even still, it does take some getting used to, but I think it helps a lot.