The latest version is more than just a cosmetic upgrade. It adds a number of new features and makes significant improvements to many existing ones. Among the new additions are several advanced editing tools including the Smart Carver, a re-sizing tool that can be used to remove unwanted objects from images while keeping the proportions of the main subject intact. It appears to use a similar detail-detection algorithm to Adobe Photoshop's revolutionary Content Aware Scaling feature, although it isn't quite fast or as good at retaining the proportions of objects in the image. It is certainly a useful feature however, and makes a somewhat quicker alternative to painstakingly clone-stamping out unwanted details.
Also useful is the new Object Extractor which uses edge-detection to help select objects from a background. It can cope surprisingly well with blurred edges or fuzzy details such as hair, and is more effective than simply feathering the edges of a point-to-point selection. The tool has to be applied manually by painting over the object, but if you use a graphics tablet this is relatively easy.
Other new features include a Vibrancy booster, an on-image text editing facility basically identical to that in Photoshop, and the ability to make HD video slide shows. More importantly for DSLR users PSP now includes a fairly good Raw processor with batch processing capabilities. It is fairly basic and doesn't have features such as lens distortion or chromatic aberration correction found in Adobe Camera Raw, but it can be used to adjust white balance, exposure, saturation and noise reduction.