In windows 8 the system is 'abstracted' behind metro. You can't access the system using conventional means, you have to launch applications from metro (unless you use the desktop or pin them to the status bar), and have to search in metro to access system configuration. In fact, it wouldn't be incorrect to say metro is the new start dialogue, since it binds to the windows key. This is as of the consumer preview, but it could change for the final release.

The 'integration', if you can call it that, is definitely no where near what it could be (task switching in metro and classic desktop are two different systems). They also introduce many new interactions for metro, that even I didn't know about till people told me (hot spot in top right, right click to access IE 10 metro controls). Of course, most touch based systems have these kinds of problems, but the question is will they be consistent across metro.

So really the best description of the system is Windows 7 with a new start dialogue that takes up the whole screen, can start applications itself, and even has its own task switching; all with some added sugar to the rest of the OS.