The start menu as we know it is dead. I miss it, but I am not going to pine away for it. I do think that the current implementation for the start screen has some issues that need to be addressed.
Mousing over to the corner is not consistent from machine to machine. Sometimes if I hover the mouse just correct, the start option and the multi-task will come up, sometimes it won't.
My suggestion would be to bring back the start button, but let it launch the start screen instead. We don't have to have the old menu, but we do need to some improvement in this interaction. A button guarantees feedback for the location and activation to the user.
Second, the start screen should have a better search system. Instead of having to dig into results to find what you are looking for, it would be better to present all results, and then allow the user to filter by type. The current implementation is search, change filter, find. It would be better to search, find, filter if not found.
Third, even though the start screen does react in a similar fashion to the old xp start menu, fly out on mouse position, it's not consistent either. Now whether this is a performance issue due to my machine, or code, I can't be sure. It's very jerky on my system and not as smooth.
Although with this release, they have added the demo on startup, I truly believe that it's not fully fleshed out. Maybe a step by step demo for those that want to use it comparing the old way to the new way would help a lot of people out. Show pressing the start button, then show mousing the start area. A look at the old menu, transition to the new "menu"/screen. Etc. If this type of demo is done, make sure that people have the option to skip out of it easily, but accessible from the desktop and start screen should people want to spend more time training later.