Please, please, please let it fix Safari HTML5 at the very least, and bring a better UI to Calendar. Thus far, iOS7 goes down as the worst major OS upgrade in Apple history after OS X 10.0 (another incomplete bit of a mess... not really usable in mainstream until 10.2).
And it's not really fair to include OS X as a major upgrade, as it was an entirely new OS. So, iOS 7 really should get worst major OS upgrade from Apple, ever. Granted, much applies to the half-finished (I'd probably rather use a different half-something adjective, but that'll do) feel of the UI, but there are technical issues too... the most disconcerting being the destruction of mobile Safari's beautiful HTML5 handling. I'm used to being proud of my Apple products... not so much with iOS 7.