If you don't have a touch screen, once again -- put your mouse cursor in the lower left corner of the screen - you should see an icon for the "Start" screen.
Click on that. On the start screen, find the icon called "Desktop" and click on that. Wha-la, Windows 7 is back.
Since the upper left corner always shows the last app you had (sorta like a toggle) if you do get into one of those big-block screens you should be able to always go back to your previous screen (Windows 7 desktop) by going there and clicking, as well.
Placing your mouse cursor in the upper right hand corner of the screen will cause a slide out that contains functions like those contained in the old Win 7 Start menu, i.e. search, add devices, settings, start, etc. If you spend a little time exploring what these do, you'll easily adapt to the new system. You basically have all the options you had before, but just multiple ways to do some things, like start applications.
People with Windows phones will also like the similarity between the new interface and their phones, I guess. I'm personally an Android guy, but Cindy likes the Windows phone.