I love how configurable Aptana Studio 3 is regarding UI style, how it lets you manage several projects and remote servers in tandem. The per-project Git integration is a bonus.
The deployment wizard is really handy for hooking a project up to a remote server in no time.
The built in console is excellent, and I use it primarily for Git, and navigating projects that contain multiple Git repositories.
The Open Resource tool (Ctrl + T) and Open PHP Element tool (Ctrl + Shift + T) are great for navigating files/classes across all projects.
The outline view is great for quickly navigating classes by their method names and allows quick identification of method visibility and scope.
Code hinting and navigation for simple to intermediate purposes works really well. Tool tips are shown for built in PHP functions, too, outlining their documentation.
It gives me everything I need to start working in a local development environment (aside from, of course, an HTTP server running PHP and a database server).
The preference menus inherited from Eclipse can be quite cumbersome to navigate.
It frequently forgets my preferences, such as PHP version for a project, or syntax highlighting theme for the entire IDE. I've gotten used to this but I shouldn't have to.
It often tries to re-index entire projects if they're introduced or change a lot, for searching and code-hinting purposes. This is slow and bloated in the sense that this interferes with UI responsiveness.
Code hinting and navigation through classes/methods in complex inheritance chains isn't up to scratch.
It hasn't been updated in years and offers no support for PHP versions beyond 5.4.
No line height configuration!
This IDE helps me work efficiently as a PHP Developer, and I'm very comfortable and familiar with its features (and its quirks).
I use it primarily to develop PHP web software or PHP libraries.