It's been less than a week since Google announced Android L and they also released the developer preview for Nexus 5 and Nexus 7 a day after announcing it in Google I/O. It is one of the biggest updates and is design focused. There are some feature additions too but the significant changes are in design. Google is using new design principles called "Material Design" for Android L.
Google is using a set of bold colors and improved Roboto font for apps in Android L. Also, there are lots of animations to give 'interaction with material' feel. Overall, the interface is much better than any of the previous versions of Android. And I am sure many folks would like to have it on their devices. But till it gets released for your device, you can always use themes. If you're on CyanogenMod version 11, there are some Android L inspired Themechooser themes available on Google Play Store.
Android L CM11 Theme is a premium CyanogenMod 11 theme which makes your device look flat just like the original Android L. Inspired by the Material Design, this theme comes packed with official Android L Wallpaper, theme for Google Keyboard, new Roboto font, new status bar icons for WiFi and Mobile Network and more. It also themes the Dialer app, Notification drawer and Calculator app.
The theme is optimized for xhdpi and xxhdpi devices and is available for $0.99 on Google Play Store.
If you don't want to pay for theme, there's also a free version from a XDA developer. The theme includes all the above mentioned features plus it also comes with Android L boot animation, Navigation bar icons, Transparent System UI, Ringtones and Notification sounds. You can grab the theme from this XDA thread.