Why try AppCode?
Because of a truly smart code editor, with

Thought-out and convenient code navigation and code completion
On the fly code analysis with quick-fix suggestions
Project-wide usages search for classes, methods, variables, resources
Instant code transformation intention actions, including i18n support
Better code refactorings: 'Change Signature', 'Extract Method', etc.

Other facts about JetBrains AppCode:

Can open and create Xcode projects
Integrates with the Interface Builder
Can run your app on iOS device or in simulator
Unit test runner for OCUnit
Has a debugger with evaluate expression
Supports Subversion, Git, Perforce and CVS version control systems