After using it for a couple more days, battery life hasn't really changed from 18. I'm tempted to say that it's better but I don't want to make any claims before I actually track battery life across a week and compare it to my battery life pre-update.

The overheating is a common occurrence, but it doesn't persist. It seems to be certain things (setting the animated backgrounds in iMessage is a good example), but the moment I'm not doing one of those things the temp feels fine. My battery does drop a percent or two during those cases (which sucks), but my typical use of the phone hasn't yielded any noticeable battery life loss compared to 18.5