That's disappointing. I tend to believe someone like VSMacOne because he details exactly what he's seeing whereas SumYoungGai just said it was smooth.
Under changes in the first post it has been reported that "App closing animations appear to be fixed on 7 Plus". So now we have reported that it's smooth, fixed and not fixed which is usually the case every beta in those topics that why I take what I read with a pinch if salt regarding this issue.
In reality as of 10.1.1 we still have an iPhone 7 with often laggy animations with choppy scrolling in the app switcher with a half assed improved app close animation and in comparison to a 6s (which is all round much smoother) you will struggle to see any noticeable speed improvements with the iPhone 7. All in all quite a disappointing phone thus far.