I'd agree with what others have said, its definitely worth getting them on a cd, if you meet characters the photographer will usually take quite a few. Also the quality of the photos will be better than most can get with their own, especially the nightime lights etc
Also if you're planning a trip to Typhoon Lagoon you can get a smaller photpass there on a strectchy wrist band so you don't lose it in the water, again you'll get photos you wouldn't get otherwise, there is one photographer in the wave pool and one round the lazy river ready to take photos.
Test track was the only ride i found to accept photo pass, i think its a bit of a con the others don't yet but thats my only grumble.
Personally I found it great, unlike Universal and Sea World where you feel pressured into having your photo taken by the barrier of photographers as you enter the park!