This software bundle is primarily for people that want to do video editing, because that's how the product synergy goes - Photoshop Elements is extremely useful for making DVD menu templates and still images that can be used in Premiere, but Premiere Elements offers very little to those primarily working with still images (the still images Premiere can pull from videos tend to flicker and be of low resolution).
So, if you're looking to buy this bundle, you need to ask yourself this question: are you interested enough in video editing to pay roughly $50.00 extra for such a program when Windows users get a basic video editor for free (most versions of Vista and XP come with Microsoft Movie Maker, but most people don't realize that they have it installed)? If you've used Movie Maker and you want something more powerful, then this package is a great deal. If not... why not try the free option first before investing in both programs?
As to the individual programs... Longer, more detailed reviews for each can be found on their individual product pages. For those that don't feel like searching, though: Photoshop Elements 6 is one of the best versions of the software I've used in years, and I highly recommend it; Premiere Elements 4, on the other hand, is much less stable than the previous version, and ended up being a disappointment. I can still recommend this bundle, but those purchasing it should be aware that Premiere Elements currently has some issues that Adobe needs to address with a patch (a patch that was not available at the time of this writing).
Note about system requirements: Premiere Elements is listed as requiring an Intel Pentium 4 or Celeron 1.7GHz (or compatible) processor (note the lack of support for AMD). RAM for XP is 512MB, 1GB for Vista. Photoshop Elements' requirements are slightly less, and are listed as only needing an Intel Pentium 4, Pentium M, or Intel Centrino 1.3GHz (or compatible) processor. Photoshop Elements also requires less RAM, and is listed at 256MB minimum.