This product is great for displaying all those hundreds of digital photos you have stored on your PC, that you might just otherwise forget. The recent updates seem to have ironed out a lot of the issues talked about here and can be found easily on the philips website.
Just shove in a memory card and see all the pictures displayed, on the 7" display, which is an appropriate size, and very clear. If you don't use or like memory cards, you can connect anything that looks like a mass storage device to windows using the usb leads supplied, and it will read the photos from it directly.
Only displays JPEGs - not an issue for me.
Brightness is ok, but you might want to brighten some of your more darker pictures. This is not a fault of the unit (it is an issue with any lcd display, and this is better than most). You can adjust the brightness, but this just alters the backlight, and you might want to change the "brightness/contrast" of the photo itself, before putting it on the memory card to display. It would be nice to have seen this as a feature on the photo frame itself (perhaps a gamma correction factor to all photos displayed). Having said all this, it is fairly well tuned to how our picture look when printed out (i.e. if they are too dark on the display, they will be too dark when printed out).
Slide show automatically rotates pictures (adding black bars), but if you manually browse the images, it won't and you just physically rotate the display accordingly. This is a great idea. The battery works for long enough to pass around friends, but really you want to run this connected to the mains, so make sure you have a socket nearby.