We have bought the photopass/memory maker several times. We have always bought it before we go, so we save a few dollars by doing that. We like the photopass - for the main reason that we are ALL in the picture. I also think that since we know we already purchased the pass we tend to stop at more photo spots. Last year we ended up with a few hundred pictures - and we did not do any fun edits on the Photopass website.
As far as lost pictures... we did have this happen during our last trip. We did get into the habit of checking each night online to see the pictures - so one night we noticed that a batch of photos were not there. We called the next am, and tech support was GREAT ... we called up, they found the pictures and fixed the issue right away.
We also had an issue with downloading the photos last year as well ... I downloaded them all - with the thought that I would look through them later, well with two 2 yr olds later ended up being a few months. When I went to look at the pictures I noticed several batches of shots (from different parks, different days, etc) were not with the download files. I called Photopass - and again, the Rep was EXCELLENT! He reinstated all my photos for me to download again, and also made a CD and fedexed to us for next day delivery. I cannot speak highly enough of the customer service I received when their were issues. While the issues were frustrating - technology can be and at least I know if/when something happens Disney will be able to make it right.