We didn't buy a Photopass CD, but we did get our pics taken most everytime we saw a photographer and it still only added up to 67 pictures in 6 days. I don't think for us it would have been a great value, plus you always want to take lots of pictures of shows and rides and "things" everywhere. I will say we did buy 2 5x7s off the card online, and the quality was great! You can personalize online with a year or pic of the castle in the corner of the picture.
It is worth hanging onto your Photopass card and letting them take your picture because you never know when a great family shot will come up that would be worth 12.95, and you never know when your camera battery will go dead (like ours did in line at Ariel's Grotto. Yikes!) But take your own camera, too, and then you can see if what ended up on your Photopass is worth $99 to get them all put on CD.