This is actually a pretty big concern of mine. I switched a few months ago to an iPhone 5 (first iPhone I've ever tried) and what struck me the most was how fluid the experience was...no stutters, no lag, no scrolling jitters...just liquid smooth. Now, every time I try a Android device, the stutters are really abrupt and obvious.
I found
this article that explains in more detail, it explains that Android will never be as smooth as iOS because Android is built of JAVA which means it runs within a VIRTUAL MACHINE on the device, whereas iOS directly access' the phone hardware, which is why a 1.2 ghz iPhone with 1GB of RAM is smoother than a Android with nearly double the spec.
I really want to switch back to Android (No simultaneous Voice/Data is frustrating), but the stutters are far too distracting. To this day, I have yet to see a Android phone without web browser scroll stutters; and interestingly enough, Google Apps like YouTube work BETTER on iOS.
Final note, a lot of people that "don't have stutters" in reality "don't notice stutters", mostly because they are upgrading from a slower device or simply arn't bothered by it. Just like how people can claim PenTile screens look beautiful and clear. It's not a dig or cut on people that say their phone is silky smooth, they just don't see it. TONS of people said the S4 was super smooth when it was WORSE than the S3, TONS of people said the S3 had an amazing screen when in reality, it was grainy. TONS of people, just like on the S3, say the S4 is amazing, when in reality...its grainy. (I loathe PenTile)
Personally, my user experience has been unparralleled on my Jailbroken iPhone, but I was hoping the G2 with its big 1080 LCD could pull me back. Looks like I may be waiting a bit longer.