The S3 does look good bit if it's anything like the S2 it'll feel cheap to hold. Don't get me wrong, they are great bits of kit. I will wait until the iPhone 5 comes out before I make any decisions though.
Been playing with my colleagues SGS3 all morning.
Screen is epic, very good. Speed is stupidly fast.
I did think my colleague was taking the piss at first though, as he is a bit of a joker, and handed me a dummy phone. It felt light and cheap to touch. Also the same android issue of selecting apps (as was the same with the SGS2) you have to push it perfectly straight, if you touch it at any angle it thinks you want to swipe, gets on my tits so much, iOS you need to put a bit of effort in to swipe anything which makes it less likely to happen by accident.
The size is just laughable though, i put it in my pocket and it felt silly after the iPhone being in there. Way too big.
Very good phone and the best on the market by far at the moment. Just standard things I dont like about samsung phones not fixed from the SGS2