Coming from the power hungry EVO my opinion may be a bit biased but I am AMAZED by the battery life in my new S3.
I’m running live wallpaper (because I like it!) and played with my new S3 all day (ok, about 4-5 hours) surfing the net, installing all my favorite apps and the NEXT DAY I still had 23% on my battery.
I have the "Auto Brightness" shut off & have my screen cranked up to full. I’m also in a fairly poor coverage area so my S3’s transmitter is working overtime to keep connected.
Again, I may just be conditioned to the lousy battery life of the EVO but… DAMN!!