Microsoft needs to work on it so that it can resize Metro apps if you want, or at the very least add some useful options to the Start button rather than just taking you back to the Metro Tiles.
This is my biggest complaint about Windows 8, and it's a deal killer for me. When I'm working, I regularly have several programs going at once, and I'm using them all at the same time. On occasion, I even have Linux running in a virtual machine and I'm using some data analysis software there while using other programs in Windows. Having everything run full screen alone makes it much more difficult, but even worse is having everything run full screen and not have a fast way to switch between programs (task bar), or even see what else is running makes the computer virtually worthless for my work. Yes, I know there's the desktop interface, but when I tried it out a few months ago, I found that the start button only took me back to the Metro interface and really wasn't helpful at all. I kept inadvertently going back to Metro without meaning to. Also, the desktop interface was on one monitor and the Metro interface on the other. I couldn't get the desktop interface to span both monitors as I needed it to. Maybe some day I'll go back and try it again with one of the 3rd party start menu programs, but for now there's no need.