It's very convenient for dealing with those quintessential shots that you just HAVE to have. The castle photo, the EPCOT Spaceship Earth globe, the pretty background photos
It makes M&G super convenient!
No coverage for Character Meals (except Ohana) though!
I still recommend one brings other cameras/devices so you can capture unique candids (Mickey Bar Time, "it's snowing?!", THIS-is-the-Avatar-line, etc) but most of that is on your phone (which you need for
MDE), unless you have photography as a serious hobby.
So yes.... I would say it's worth it as pretty much you don't need to think about anything until you get home and then you have a month to get them all DL'ed. Also with MM, if you have people listed as Friends & Family (which you will need to do anyway if you are scheduling ADR's or FP+) the photos THEY take throughout the Parks show up on YOUR account. They can't see your photos unless they also buy MM.
But this method is how we found my family members on part of Day 1 of the trip... we realized they were going to make it through the gate lines about an hour ahead of us (and the ADR time!), so I said, go get your photos taken and have them scan your ticket card, it's free ! I know it *wasn't* free but my mom doesn't have MDE and her phone is too old for it. she would never get the hang of it, so I just asked her to take some tourist photos and we'd meet her somewhere in the HUB. Meanwhile we have gotten through security, through GS, through the Gates, and we are outside the Theatre when my DH does to buy MM. The morning parade is starting so now total chaos of people... Mom somehow finds us but later in the afternoon, we are in different groups. they said they'd be in Frontierland... somehow they didn't make it past Adventureland and we figured this out because they had some other MM photos taken and my DH's MDE was so helpful in telling us they were by POTC!
Side note: totally understand how this feature allows Disney to track our every movement.