Got the update last night after my impatience caused me to force the update. First thing that I noticed was the size. This update was 1.8mb on the Nexus 4, but 16.6mb on the S4 GPE. They clearly had to change more things on our device.
The only things that I definitely noticed are that the camera firmware was updated (not sure yet what was change with it) and that my phone is making use of roughly 20% less RAM when idle (likely a result of me flushing some things and not the update itself). I'll post if I notice anything, but so far I'm going to assume that any perceived performance gains are placebo.