dpreview.com has posted a nice review of Adobe Photoshop CS2 that touches on several of the new features, comparisons to alternatives (such as using PTLens instead of the new Lens Correction tools), and a fair-minded conclusion:

At US$149 or 25% of the US$599 price of the stand-alone full version, this upgrade comes at a reasonable price tag, preserving most of your original investment in an earlier version of Photoshop. If you are still running Photoshop 7 (or an earlier version), it is certainly worthwhile upgrading to Photoshop CS2 now as you get two (or more) upgrades at only US$149.

Seen here.

Other Photoshop CS2 reviews here, here, here, and here.

Buy the PS CS2 Windows Upgrade at Amazon, (or Mac upgrade, Windows full version, or the Mac full version).