I uploaded the new firmware on to my D70 about the day after it came out. I suppose you could say that the AF was slightly faster, as 3Dguy says it is better at predicting how many exposures you would have left, different look of course. I'd say it was worth it, since it's free and not too much hassle to do, but unless you are a 'statistic testing nutcase' then don't worry too much, your not missing anything radical :) either way, have fun!