This is just completely overdone for a phone in this day and age. And I bet you it's still not as smooth as the iPhone 4S. [Source]
Just so you know, Samsung has made no official announcement on it yet. "Leaks", but nothing real yet.
Smooth as the iPhone 4S? Last time I checked both the Galaxy S2 on Gingerbread and the Galaxy Nexus on 4.0 were as smooth as the iPhone, all while rendering much more content...I don't see why you would think that they would take a step back and make it laggy again?
Devices that hundreds upon hundreds of people, ranging from children to grandparents mess with on a daily basis seems choppy? No way.