None at all, if you're setting them up correctly. 100-150 nits (cd/m²) is just about right. I color-calibrate my monitors and this is one step in the flow. I calibrate to 120 nits and find that it's consistently about 33% brightness. Calibrating this way, I can look at a full white screen (think "blank notepad window") with no particular eyestrain.

When I went from BlackBerry to Android (Samsung), I noticed the Android was much dimmer, though BlackBerry devices had gotten brighter. My experience is from 8700c through 9900 Bold.