Here is a picture of the Windows 8 Samsung tablet given out on Tuesday. It looks very smooth for the most part. However, given that this is a developers' prerelease version there are inevitably some rough edges here and there.
A very cool feature of Windows 8 is that when you don't use an application all of its processes go to s suspension mode. So, it stays in the memory but doesn't use any CPU. See my task manager a few seconds after I moved away (didn't close) my IE and piano apps. This should save a lot of energy and also make visible apps run a lot faster.