Old start menu is something I would call bad design. It was good improvement in 1995 but since then it became one of most useless features.
I'm not saying the old start menu was perfect. I just think the Metro replacement is crap.
The metro start screen doesn't replace the start menu, all of the functionality that is currently part of the start menu is seperated out & you can use Windows 8 without ever using the start screen.
Yeah, RIGHT clicking an invisible area in the lower left corner to get to some of the old start menu functionality is not intuitive.
Edit: Actually the metro screen does replace the start menu. It's labeled "Start" and if I hit the key to bring up the start menu Metro is displayed.
One of the most common things I do in Windows 7 is hit the left windows key and then start typing the name of the application I want. Makes it very easy to launch apps. Guess where that takes you in 8...