wow, 600 nits -- that's bright. If you have a mac book pro you already have a screen that does 500 nits which easily lets you see the screen in the sun. If you're inside without glare you can get away with just 250 nits. For smart phones -- the nits are typically much higher because people use them in the sun and need good visibility outside.

A 600 nit screen inside would almost be too bright for some people. I know people who already turn down their laptops because 500 is too bright. but i think its good to have the option to turn it down rather than a screen that's too dim.