I have the latest model 24" Alum iMac. Whilst I like it for everything else, I have been unable to color balance it due to the glossy reflections, uneven lighting and glare.
The white 24" iMacs were OK.
I am hesitant to buy the rather expensive Cinema displays, just to try and fix the problems on this model. It seems financial overkill on what is supposed to be the more affordable option. Or at least it used to be before Apple changed them.