It's not worth it for my family, but YMMV. We purchased it for our lost trip. The on-ride photos are nice, but all too grainy/blurred to do much with, and we had at least one set that didn't "come out" due to a glitch with the on-ride camera (flash was out of sync, according to the CM). Other than that, the photos we got were no better -- and in many cases not as clear -- as the ones we had CMs and Photopass photographers take with my own point-and-click Canon from home (a camera that cost less, incidentally, than Memorymaker). We ended up coming home with 150+ Memorymaker photos (about 25% of which were good) and 400 photos on my camera (about 50% of which were good), and used them to cobble together a Shutterfly photo book of our trip which was a great keepsake for everybody, but which I could have put together just as easily without Memorymaker.
(Also, I'll be blunt: I think the "magic photos" with Photoshopped characters are silly -- although millions of people clearly disagree and are delighted by them. If they are something that you like and you don't have a Photoshop whiz in your family who could do them at home, Memorymaker may be worth it to you for those alone.)