The Start Menu, as introduced in Vista, wasn't fit for modern computing. It was confined to a small area of the screen, had limited customisation and was awkward to use, especially when trying to browse applications. The Start Screen improved upon it in many ways, notably in customisation and the ability to display large numbers of apps, but is a little cumbersome on the desktop.
If the new Start Menu is size limited then I fear that will hurt usability but if it scales for larger displays then I'm all for it. One of the major disadvantages of the Start Screen is the amount of wasted space if you only want to display a handful of apps - the new Start Menu will eliminate that. Basically, I want to see how it works in practice before passing judgement on it. It could be an improvement, it could be yet another compromise.
At least it shows that Microsoft is responding to user criticism. The backlash towards Vista resulted in a new direction for Windows 7 and hopefully we'll see the same thing here. I want to see the Metro design elements removed from the desktop - I despise the Charm Bar, I hate the Metro Switcher, I detest the Metro tab that appears when you click the network icon and I hate that some computing options are only available through PC Settings. Those elements are great for tablets but they are a nuisance on the desktop. Unfortunately we'll probably have to wait until Windows 9 for that.