Since several people have asked the exact same question I decided to throw up a quick post on how to go back to the classic interface in Ubuntu 11.04 'Natty Narwhal' rather than the new, swish looking Unity UI.
It's actually pretty simple to choose between Unity and the classic UI.
- Log out of Ubuntu 11.04
- At the log on screen select the user you want to log in as
- At the bottom of the screen you'll notice a task bar appear - this allows you to switch between different modes
- Select Ubuntu Classic
- Log in as normal
- If you want Unity back, repeat the steps but instead choose Ubuntu