Pros Cheap, uses USB memory sticks, fairly easy to operate, pictures are bright.
Cons Manual is poor. Apparently no additional online support. A little picky about image creation, low resolution (standard for this price range)
Summary I had some frustration initially with the SD7021. I use GraphicConverter on the Macintosh to edit pictures, and it doesn't recognize the output files for some reason. Pictures were garbled or blank, slow to load, menu unclear. Once I found I could use the Preview App (comes with Mac Leopard) to re-save the files into the final directory, and then things would show up, it made my day much better. USB stick and SD card worked fine, but if the USB stick is lighted on the end it will be distracting as it's partially visible from the front.
Aspect ratio is 16x9 (1.78:1), supposedly it has 480x234 pixels (2.05:1), but pictures at that size had black bands on top and bottom. Elsewhere in documentation it says 720x408 (also 1.78:1). I didn't count pixels in the frame, but pictures at 720x408 worked best, maybe it's really 480x270. This is closer to standard landscape picture size, so I view it as a bonus.
You can choose the amount of time each picture is displayed, and the transition style. You can set the clock and apparently display it over the picture if you want (I didn't). But the clock settings don't survive turning it off and on, so unless it's on 24x7, this is more hassle than it's worth (did I miss a battery somewhere?). For standard startup, you need to press the farthest right button twice for the slideshow to start.
Good item for a grandparent or casual display, but not for a videophile (they still require more $). I remember seeing a digital picture frame on Star Trek:NG (Captain Pickard's quarters) and thinking "That's cool...everybody should have one of those someday..."