Gaming performance in 8 is better.
Start Screen is good, only if you know how to use it, which the video you posted moronically doesn't.
Windows 8.1 which will be free for Windows 8 users, has a long list of improvements throughout the OS, plus new features.
For the Start Screen improvement in Windows 8.1: it takes Windows 8 which was a bit too tablet optimized, and creates a better balance for PC's. This is clearly something that Microsoft will continue to work on and polish with every version of Windows, to create this perfect balance between different types of devices where Windows run.
I tried those Start Menu replacement and pretty much all are crap. Especially the free ones. While they work, they simply don't have any close to the polish of Windows 7 start menu, and doesn't fit in Windows 8 at all.
You are better off learning the Start Screen. Once you learn how to use it, you'll be comfortable with it, you'll never look back, especially in Windows 8.1
If you want to see my start screen (old picture, but the idea is there):
As you can see from the above, I have my pinned folders.. I can pin any folders I want for easy access to them, something you simply could not do with Windows 7 Start Menu. And everything is organized for the most used item at the bottom left corner to the least used to the far right. As for my applications, the reason why they are on the far right, is because the most used ones are already pinned on the Task Bar, so why have both?
Another cool thing is the ability to pin your games all in 1 place. While the screen shot above shows few games (that's because it was taken while I was installing my games), in 1 click, you get to start your game. No need to Open Steam, and Origin, And Uplay, and try an figure out where your darn game you want to play is in which service, and even if you know, you need to pass through multiple clicks to access them.
If you are more gamer oriented, you can drop my News section and Productivity section and now you'll have your games closer to the rest, and more room without scrolling.
Basically, my layout follows Microsoft guidelines:
It might seam bizarre a bit now, but once you are used to it, you won't enjoy the Start Menu anymore, as things wont' be quick access anymore.