We used MM during our Christmas vacation (12/20-1/4) and had only a few glitches that were not uncommon to PhotoPass prior.
Our first ride photo of the trip never showed up on our account even though the PP kiosk could see it was pending but never made available. The ride was Test Track and the image was not very good as the group in the front row was holding something up and blocked my son anyway therefore not a big deal and our photo from 'Ohana was of another family for some reason, this was using the receipt they provided with our prints that should not have been printed in the first place.
All in all, we have 390 photos including attractions, character and general icon shots. We have not done any photo editing yet such as adding borders, or other modifications before downloading so I don't know how the download process will work just yet but will update over the next few weeks as I get time to dig in start working on them.
My main complaint this year is there seem to be fewer photographers this visit than in any visit prior with PP, this may be perception but it used to seem like there were photographers everywhere but not anymore. However many of the photographers took more shots and took more time individually with my family and I, many really seemed to care about their work and took time to get the right angles and setup the shoot which really made us happy with the service.