I have to say that in my experience(brief, limited) with OSX, brightness hasn't been a problem. Either on a crt or on the powerbook's lcd.
I don't ever use the little contrast and brightness buttons built into my powerbook, but since they're there, I suspect that some folks might.
I also suspect that these options were probably left out in the beta and that we'll have all sorts of options in the Monitor Preferences in the final release.
The anti-aliasing does bother me more on the powerbook than on a crt. Normally in os9 I have anti-aliasing turned off. I use the excuse that it's faster, but truthfully(personally) it does bother my eyes. Again, more so on the powerbook than crt.
I'm hoping that the final release has at least the same options that 9 has, where you can choose whether anti-aliasing is on or off, or only after a certain point size.
Kind of off topic, but I think it's somewhat related. Try this: Open a classic app(i'll use netscape). Once it opens, resize the window. Notice how it makes that outline(really quickly!) and when you let go, the window snaps to that size?
now open a cocoa app, or even just a finder window, and resize it. No-outline, it resizes the window to as you move the mouse around., with the button down. Notice how slow it is?
In just about any window manager, you can play with these settings(*nix users, think WindowMaker) to adjust the window resizes to fit your personal(or hardware) preferences. I'm sure we all want cool transparent windows that dynamically resize, but if your hardware isn't up to the task, I'll settle for the fast yet not so cool outline method.
My 2¢