To upgrade or not to upgrade: that's generally the question when confronted with a new version of Photoshop. And, at least for 2007, the answer is an emphatic "yes," if only because of several extremely useful new enhancements that should benefit most users, as well as improvements in performance to benefit all. Furthermore, if you traditionally use Photoshop for video postproduction tasks, 3D texture-map editing, or scientific image analysis, there's a whole new--and pricier--version of Photoshop for you, dubbed Photoshop CS3 Extended.
From loading to saving, Photoshop CS3 generally operates faster than Photoshop CS2. There is one performance caveat for the CS3 suites as a whole: it's the slowest, most painful installation I've experienced in years, and that includes bloatware like Microsoft Office 2007. Thankfully, you only have to do it once, maybe twice. Once you've snailed your way through it, though, it settles into the back of your memory like the 10 miles of construction that blocked your commute home for a few hours.
The improvement in start-up time alone may be worth the price of admission. A cold load under Mac OS X 10.4.9 (running on a tricked-out octocore--two quad-core, 2.66GHz Intel Xeon CPUs--system equipped with an ATI X1900 XT card, 2GB of RAM, and many hundreds of gigabytes of free hard disk space) ran about six times faster than CS2, and when I'd already launched and closed the app before in the same session, it seemed to cache pieces, making the launch more than 36 times faster. The Mac version shows exceptional speed gains across the board, as well. CS3 ran the CNET Labs Adobe Photoshop image-processing test almost 60 percent faster than CS2. Surprisingly, the Mac version ran CS3 significantly faster than Windows; it took more than twice as long under Windows Vista, and I estimate just under twice as long on Windows XP. I extrapolated based on previous CNET Labs' tests showing that Photoshop CS2 runs about six percent slower under Vista than under XP and on data we have for Photoshop CS2 on the same test bed running Windows XP. Take it all with a grain of salt.
Though there's little in Photoshop CS3 that you couldn't do before, enhancements to existing tools really streamline production work. These include Smart Filters, which apply the traditional Filters at render, rather than on the bitmap, resulting in nondestructive, re-editable effects; Refine Edge, which groups selection-edge tweaking options in a single dialog with various types of previews; and a Quick Selection tool which speeds up masking against certain types of backgrounds, such as patterns. In addition, enhancements to Bridge CS3, which Adobe bundles with both the standalone applications and suites, finally provide Photoshop with a decent media browser. Adobe updates its 32-bit high-dynamic-range imaging support with enhanced algorithms for its Merge to HDR capability, but it puts all the beefed-up HDR-editing capabilities in the Extended version.
There are, of course, a few new capabilities, though they'll probably be handy for only a limited group of users. You can export images for Zoomify, which deconstructs images into smaller tiles and creates a small Flash movie that you can embed into a Web page, effectively allowing you to zoom in on larger images. And the automatic Photomerge will probably be a hit with panorama constructors.
For users new to image editing, Photoshop's rather monolithic learning curve remains, and you're better off starting with an inexpensive application such as Adobe Photoshop Elements 5 or Corel Paint Shop Pro XI. One of those may be all you need. But if you've been waiting to take the plunge, Adobe Photoshop CS3 is as good as any version to dive into, and if you're a pro considering the upgrade, it's probably worth the $300 or so bucks it will cost you. As for enthusiasts, that difficult decision remains between you and your wallet.