I don't see a big difference. No difference in speed or smoothness. Google Now is mildly interesting. It doesn't seem configurable so I can't tailor which cards show up. I think it will add nothing.
I use Go launcher. It is and has always been better than touchwiz so the improvements in touchwiz aren't of use to me. I did try it but there is no significant customization. I can't even change the animation when you move screens.
Once again, lots of hype...no real change. BTW, I see a new application S Suggest. It doesn't load though. Anyone know what that is?