I do short trips with 2 or 3 park days and I just don't feel MM is worth the cost. We don't do a lot of photos to begin with. The ride photos don't really interest me. I like to look at them online right after, but don't feel the need to save or print them. The character handlers are always more than happy to take a few pics on my own camera and most of those have turned out fine. On the rare occasion I come across a character with no Disney photographer and no handler, I just ask another park goer to take a couple of pictures on my camera and offer to do the same for them. I did purchase one photopass photo last year. It was taken at night, looking down Sunset Blvd at HS with ToT in the background and the photographer had asked us to make faces like we were scared. The picture was so funny I decided to purchase it. $15 seems a bit much for one picture, but this is one that wouldn't have come out nearly as well if I had asked to have one done with my camera, so I deemed it worth the cost. Individual downloads are $15 regardless of the source (Disney photographer, ride photo, magic shot) and include a release to allow you to do pretty much whatever you want with the photo (post online, make prints, print in a book, make some other kind of photo gift item, etc.). I think you really just have to look at how many photos you think you might have taken and of those, how many you think you would want to have copies to keep, as well as whether you want to be able to have copies of ride photos to keep, and then decide if the price is worth it to you. You will be able to view all of your photos online even if you haven't purchased MM, so you could always wait and see what all you end up with and make a decision after the fact. Only down side to that approach is that I think it costs more that way than it does if you purchase prior to your trip.
