It does appear to be minor changes on the face of it, so i'd imagine the bulk of the update is under the hood stuff.
I tend to wait to see what EverythingApplePro on Youtube say about it as the guy is usually pretty thorough when he goes through each update.
We'll see how the battery goes though - I charged to 100% and updated to Beta 5 without unplugging and unplugged at 11pm fully charged and updated.
I still don't know why they don't do something like the Pebble Watch's "idle mode". They could check to see if the phone is unused and on a flat surface for at least half an hour and, if so, automatically activate low power mode. It could arguably extend the battery life by a decent amount, especially for most people who don't use their phone overnight.