RED HERRING  I never liked extra /opt or /sw hierarchy in addition to /usr/local and at some moment decided to stay away from all ports. This allows me to stay on the bleeding edge of svn.cvs/git and learn few things :-)  
(Version 6.5.5)

MARK EVERITT  There's no reason not to install bleeding edge stuff into /opt/local/ or /sw/. It can get complex, but the added niceness is that it's not in a directory hidden from Finder. If the worst comes to the worst, you can always just delete all of /opt/ or /sw/ without worrying too much.

Having said that I use the one installed with MacTeX most of the time!  
(Version 6.5.5)

MARK EVERITT  Did you just not bother to read the comment immediately below yours?

Imagemagick simply has too many features to wrap in a gui, and many people use it from scripts. Take a look around the internet. Anywhere you see a thumbnail it's probably imagemagick doing it. I use it for that and many more things.  
(Version 6.5.1)

BRSMA  You do not seem to take into account that

a) there exist some more types of graphics workflow besides ‘interactively creating and touching up images by hand’. Think of batch processing. Though there might also be e.g. GraphicsConverter, the abilities of ImageMagick surpass it by far. (Not even speaking of Photoshop's comparably extremely lame and pathetic batch jobs.)

b) there is no GUI running on servers. That is: besides web apps, mostly. But if these need image processing capabilities, it is done in the backend – i. e. mostly by ImageMagick or something similar.

And then, you should not underestimate the power of the command line when it comes to abstraction. The GUI as we know it is quite challenged in that area.

Anyway, ImageMagick is by no means software that is intended to be used by the average (i.e. GUI-dependent) end user. Most people, including myself, who actually have use for its features do not seem to mind the least not having a GUI for it. (And putting GUIs on CLI tools mostly fails, anyway – the designs/concepts are actually just too different.)

And that's from someone with an MFA in visual communication (aka graphics design) ;-) (Ok, I'm probably also a geek and the majority of my colleagues might think differently in that matter.)  
(Version 6.5.1)

MARK EVERITT  One other important thing!

IF you use a CLI then you're encouraged to think about tasks programmatically. This encourages consistency and thought rather than point and click which sometimes makes ideas too easy to realise.

This is going to make me sound a bit mad, but I actually avoid GUI for image creation, opting for PGF/TIKZ (you may have heard of this or use it if you're into LaTeX) because it keeps things consistent and forces me to think; a must for technical drawing and scientific diagrams.  
(Version 6.5.1)

PENGUIRL  I can see by your comments that it does have it's strong points, and I myself have run into Photoshops batch processing limitations, but at the same time a CLI graphics app will inherently have shortcomings of it's own. Never having used ImageMagick I have no way of knowing what they might be, but one thing that comes to mind is that it must be difficult if not impossible to clone stamp in a CLI. Or anything else involving working on specific areas of an image.

Yes I did read the comment before mine, however I did not open up the replies. My comment wasn't meant to offend, it was a serious question.  
(Version 6.5.1)

MARK EVERITT  I'm sure that you could coerce Imagemagick into tasks like clone stamping, but you're absolutely right that this is suited to a GUI. I tend to use Imagemagick for all those cases that are repetitive and could be handled in batch, or if what I want is something really simple, like creating a thumbnail. Most of my work is in technical drawing, not with photographs, so a very high proportion I what I do is programmatic anyway and I've never had a need for photoshop. I'll occasionally use gimp to touch up an image.

Sorry if my response to your initial post was harsh. I know that it was a legitimate question. There are just easier ways of finding out the answer though. A quick visit to their site would have answered your question and saved you time in the long run. Having said that I really do enjoy conversations like these! I guess, as in most things, the key is compromise. I reckon you should give Imagemagick a go next time you run into batch problems in Photoshop or something similar. It sounds like you're far more advanced than me when it come to real graphical work! I must confess I had to look up clone stamping.  
(Version 6.5.1)

SJK  From Pixelmator | Tech Specs:

ImageMagick is an open source technology to create, edit, and compose bitmap images. It is used as a core for Pixelmator  
(Version 6.4.6)

MARK EVERITT  Imagemagick is far too full featured for a single GUI! You could happily have multiple programs for various tasks and still not use it to its full potential.  
(Version 6.4.7)

WEBCHICK  Not every program can be written to fulfill everyone's needs and skill sets. This is a venerable set of (mostly) command-line tools that will find the most use by developers, particularly those who work in a multi-platform environment. Its strengths lie primarily in the usefulness of these tools in scripts: whether it be processing one image on-the-fly or batch processing thousands of images. There are plenty of fine freeware GUI image processing applications out there, so if you're not looking for command-line image processing tools geared for developers, move along and no whining.  
(Version 6.4.8)

TEKL  Can sips sharpen images or it there another way like using Quartz filters?  
(Version 6.4.3)

ANONYMOUS  read the documentation for sips, and read the documentation for imagemagick.

imagemagick does many, many things that sips doesn't  
(Version 6.2.3)

ANONYMOUS  ImageMagik is cross platform -- which is useful if you've already written something using it that you're moving to a Mac, or if there's a possibility of the software being moved to some other platform in the future.  
(Version 6.2.3)

GREG RAVEN  Well for one reason, some of us need ImageMagick because Movable Type virtually requires it.  
(Version 6.5.5)