My problem with AppCode was that the syntax of Swift was still undergoing rapid development, and AppCode lagged too far behind. So AppCode wouldn't understand parts of my code unless I avoided the latest (often very valuable) additions to the language.

When it did understand my code, it was much better than Xcode for navigating and refactoring.

Also, AppCode couldn't edit or even display XIBs so I often had to keep Xcode running alongside it anyway to edit XIBs and make connections between XIB and code, and that was a hassle.