Add to the bad that there seems to be no support to edit info.plist and all the many build settings available in Xcode. Also there seems to be no support for assets aside the app icon. In a project with at tab bar controller the tab bar icons are treated as if not there at all. You have to configure app code signing in Xcode as well. Having no way to work with storyboard files also means that you have to establish and manage your code-storyboard connections (Actions, Outlets and such) in Xcode.
Appcode as every JetBrains Tool is good at supporting version control, however, as long as git/github is your version control system, Xcode support is par if not better. Look at the video here:
I know Intellij Ultimate very good as it is my java development tool and I have yet to learn wether it supports marking changes of others in my code while I am editing it. Xcode can.
Aside from editing storyboard, xib, info.plist and asset files aside from the appicon you have to resort to Xcode when it comes to shipping your app to the store.
As for the editor code completion, code checking and snippet support are par in Xcode. As are the find/replace features.
So if one does not use another version control system than git/github, why would one want to use AppCode instead of Xcode? It would be just to avoid learning a new tool. Which you can’t after all if developing native iOS applications given all the missing but needed features in AppCode.