While the latest version of Android version 4.3 has made it’s way to Galaxy Nexus devices and Google Play editions of the HTC One and Galaxy S4 , most of the users around the globe will have to have a little more patience but you could have a view of what the Cyanogen 10.2 Nightlies which is provided by a known source.
The creators of the popular CyanogenMod custom ROM for Android are busy incorporating many of the updates from Android 4.3 into the latest nightly builds for their recent 10.2 release which is not easy to do but they are working to deliver the best. Practically , developers will really gain a lot from this an amateur Android users can learn a lot. Also remember that we are not responsible if any malfunction is experienced by your device upon installation. Device compatibility vary from device to device.
Download Android 4.3 Cyanogen 10.2 Nightlies : Download Source