Even though I've downloaded , which includes turn-by-turn voice navigation, I inevitably fall back to the iPhone's Maps app. It's hard to avoid when tapping an address in the Web browser or another app, because there's no way for them to send you directly to Mapquest. The iPhone's been without voice-guided GPS for too long.
Wireless iTunes Sync
In a perfect world, iPhone users wouldn't have to rely on iTunes to update their software and sync their media, but I'd settle for OS updates and multimedia sync over a local wireless network. This is technically possible--Apple has rejected an app that does it--we just need an official solution.
Better Notifications
iOS's big blue box for text messages and other notifications has got to go. It's intrusive, and offers no way for users to view notifications in the order of their choosing. Android's pull-down notification bar is better, but iOS could use something a little more noticeable without being impossible to ignore.