Hi Lois,
Photopass is basically an opportunity to have Disney take guest photos with no obligation to purchase whatsoever. Throughout all the 4 parks. 2 waterparks, and some dining locations. Disney photographers are scattered around in prime photo locations (such as the castle in the background) who will take photos and then record the information onto a small card, much like a credit card. You can actually have a variety of photos taken: just mom/dad, just kids, entire family, etc. I would write down the number on your card as a precaution in case you lose the card.
Once you are near the completion of your trip, you can visit In-Park PhotoCenters to view your photos and order prints. But I find it much easier to wait until we return home and view the pictures online where I can then edit the photos and add magical touches such as borders, characters, etc., in a more relaxed environment. Prints can be ordered from home as well.
Guests also have the option to order a PhotoCD of all the Disney Photopass photos to do with as they please then since they now have the rights to the photos. Additional merchandise can be ordered such as mugs, mousepads, t-shirts, etc. I am currently finishing up a professional scrapbook from our Photopass photos, but what I really like is that I was able to upload my own personal WDW trip photos to mix in with the professional ones. For me the one downside to this is that I am limited to 30 days to complete this, so I need to avoid procrastination -- a weakness of mine. It also doesn't allow me to resize all the photos to fit into the scrapbook easily.
But with all that said, I really think it is a great opportunity for guests with very few negatives. If you'd like more information and sample photos, you may want to visit the website www.stitchkingdom.com .