Why use Aquamacs instead of the stock Carbon or X11 Emacs on the Mac? Here are some features that Aquamacs has to offer on top of all the advantages that come with Emacs:
Fonts just work, right from the menu: The Mac-standard font (Lucida Grande) is the default for editing text, and the mono-spaced Monaco is used to other modes. These fonts are nicely rendered with antialiasing. Aquamacs offers a range of proportional and mono-spaced fonts to choose from.
Aquamacs has a standard Mac menu with entries where you would expect them, and recently used files are available from the File menu.
Aquamacs gives you all the standard Mac shortcuts like Apple-S, Apple-C, Apple-V - everything that you're used to in addition to the fast, traditional Emacs key bindings.
Aquamacs can organize the files that you're editing in tabs. This preserves screen space but allows you to keep track of all those open files easily. You've probably seen the tabs in Safari, Firefox or the OS X Terminal program.
Aquamacs can open a normal OS X window for each file that is opened - Emacs experts call such windows frames. Finally, Aquamacs makes use of the capabilities of windows on modern graphical user interfaces. This is configurable with a mouse-click - of course, You can switch between the windows (frames) with the "Window" menu.
Perfect Team-play. Clipboard operations interoperate with other Mac apps. In Aquamacs, if you mark a chunk of text, it will NOT be automatically copied into the clipboard - unlike in GNU Emacs. Just like in any Mac program, you can copy with the Apple-C command, and then replace another region by selecting it and hitting Apple-V (Paste).
Spell-Checking. Aquamacs spell-checks your documents with the OS X spell-checker, supporting more than a hundred languages and system-wide user dictionaries.
Unicode Support. Aquamacs reads and writes files in all Unicode variants. In addition to the input methods provided OS X, the Aquamacs Multilingual Environment defines configuration settings for Chinese, Japanese and Korean on top of the standard Mule.
Printing just works the way you expect it to - with a preview and through the normal printing infrastructure.
Meta Key Management: since Emacs uses an extra modifier key that is not on your keyboard, Aquamacs allows you to use the Option key. But even when using Option for Meta you won't lose the ability to input characters such as [ or \ with the most common non-English keyboard layouts. Alternatively, you can also use just the right-hand side Command or Option keys for Meta, or many others.
Auto Faces: You can define fonts and colors as defaults for a given editing mode. That means that you can have customized designs for different types of files you're editing. For example, you can easily distinguish LaTeX files on the screen by their beige background color, or use variable-width (proportional) fonts for text modes only, but stick to fixed width, monospaced fonts for editing code.
It's a distribution that comes with the latest goodies pre-installed so you can simply use them and get on with your life. No installation, no setup needed. Here's what's included: AUCTeX for comfortable LaTeX editing, ESS (Emacs speaks Statistics) as an interface to statistics applications such as R, SPLUS etc., nXML for comfortable XML editing. Other, smaller, packages provide support for a range of programming languages and other formalisms. High-quality Java and Lisp support is available via JDEE and SLIME, respectively. These can be installed separately via the MELPA repository.
Aquamacs offers a dedicated manual plus the good old Emacs manual directly via Apple Help environment - you can search both of them quickly with Spotlight and read the documentation comfortably.
A number of extensions to GNU Emacs are contained that would be expected of any Mac program: they're small details that make your life easier. For example, there is a "Reveal in Finder" function, or another one to open new files in one of many popular modes. When you double-click a file written in Aquamacs, it'll open in Aquamacs. Drag&Drop works perfectly. You get a menu with recently edited files without any configuration. Copy and Paste know about word boundaries, inserting and deleting spaces where sensible (`smart-spacing-mode').
Aquamacs remains extensible, so you can use special syntax coloring setups or enjoy embedded CVS, Git, Bazaar, SVN and Mercurial support, a HTML markup menu and the like. Aquamacs is compatible with GNU Emacs.
Great Support. A community around Aquamacs (and a larger one around Emacs!) will help you out when you don't know how to do X. Just write to the mailing list (but check the manuals first!)
|⌘N||new-frame-with-new-scratch||Open a new empty window/frame|
|⌘O||mac-find-file-other-frame||Open a new window/frame with a file|
|⇧⌘S||mac-key-save-file-as||Save as (using file panel)|
|⇧⌘O||mac-key-open-file-other-frame||Find file in another frame (using file panel)|
|⌘A||mark-whole-buffer||Select all text|
|⌘V||cua-paste (yank)||Paste text|
|⌘L||goto-line||Go to specified line|
|⌘M||iconify-or-deiconify-frame||Minimize window to the Dock|
|⌘Q||aquamacs-save-buffers-kill-emacs||Save file, exit program|
|^;||toggle-pass-option-to-system||Toggle: allow input of special characters with Option key / use Option key as Emacs Meta key|
Aquamacs additionally activates a number of packages that are provided with the default emacs, such as cua-base, ibuffer, recentf. The GNU Emacs code-base is patched. Please see the CVS for the collection of patches and additional source-files.