A lot of Mac photographers remember that Adobe took a long time to get Elements on the Intel platform. In that void several independent competitors appeared. I started using Pixelmator shortly after it came out and it has quietly replaced Elements for me.
Pixelmator is a $59 pixel pushing beast. It uses your graphics card and makes quick work of most common graphics tasks. Pixelmator delivers many (but not all) of the core features of Photoshop in a better, and more Mac friendly, interface. The general layout is very similar to Photoshop. It even recognizes most Photoshop keyboard combinations. It uses a dark grey interface similar to Apple's Pro applications that is easy on the eyes.
Pixelmator ships with tools, masks, layers, and several useful image filters. I primarily use Pixelmator with photographs and there is the usual assortment of levels, color curves, balancing and other photography tools. I really liked the way it renders gradients in real time. I, frankly, don't need a lot of tools as Aperture has become so robust. When I do need to roundtrip to an external editor, Pixelmator is usually enough.
Having used Pixelmator for some time, I'm also impressed with the slow march of new features the developers are releasing with each new update. They are not throwing in the kitchen sink but instead spending time on UI design and polish with each new feature.
Once your image is done, you can easily export the usual formats including PSD, TIFF, GIF, JPEG, PNG, and PDF just to name a few.
While Pixelmator most certainly is not Photoshop, it is feature rich and a respectable competitor with Photoshop Elements. In my testing, I found Pixelmator easy to use but with fewer bells and whistles than Elements. At a fraction of the cost of Photoshop, you really can't go wrong with either application. Regardless, the Mac polish and excellent interface make Pixelmator the winner for me. For $59, it takes care of all of my imaging needs. You can download a free trial from pixelmator.com.
You can listen to this review on Surfbits MacReviewCast #218.