Just as with iOS 6.1.1, Android 4.2.2 is a bug fix release. Apple's release on Monday was a fix to 3G connectivity on iPhone 4S devices (the iPhone 4S, unlike the iPhone 5, does not support 4G LTE).
Android 4.2.2 is -- similarly -- rather limited. It fixes Bluetooth audio problems on Nexus phones and tablets. It's unclear if the fixes will be ported to other devices -- those which have OEM modifications such as Sense and TouchWiz -- but the update was first seen on the global Galaxy Nexus, and reports are it is reaching Nexus 7 and Nexus 10 tablets, too.
At the time of this writing, it hasn't been seen on the Nexus 4, but since that is Google's latest developer phone, and the latest to sport unmodified pure Android, it's almost certainly due for an update, too.
The minor fixes in Android 4.2.2 include an issue in which where audio streamed over Bluetooth would "hiccup" or "skip." A report on Reddit indicates that Bluetooth streaming is still imperfect -- it "works better [than before], but it's not perfect."
The user, WeeManFoo, added that his Galaxy Nexus still disconnected from the Bluetooth speaker in his car when switching from wi-fi to 3G, pointing to more issues with Bluetooth streaming.
A full changelist hasn't been posted yet, so it's unclear if other changes are included in Android 4.2.2. As usual, the Android release appears to be staged, so if your Nexus device hasn't received an update yet, don't be concerned. It will probably hit your device in the next few days.