Because ramdisk and kernel modifications were made to accommodate Android L on the HTC One (M7), there is a good chance that the phone won't run like you would expect it to. If you want to take the chance, you can click on the sourcelink for all of the directions. Right now, the features not working include Wi-Fi, data, Bluetooth, sensors, camera and sound. GPS, though, is working.
The Android Developer Preview, was designed to show developers (natch!) and others what functions would be on Android L, and what they will look like. If you tried to port it over to your HTC One (M7), let us hear about it. You can drop your comments in the box below.
source: XDA via AndroidAuthority