If you end up getting it, make absolutely certain to get in well enough in advance (at least three days, I think) to get the $50 discount. Obviously, that helps significantly in justifying the cost. As for the MM itself, if you are planning to ride things that include a ride photo, and if you tend to stop for PhotoPass photographers on a regular basis (or are willing to do so), then it can end up being a pretty good deal. $149 for a bunch of ride photos that would otherwise cost you at least $20 a piece (assuming you'd otherwise be buying them, of course), along with tons of other photos, whether with characters or just around the parks or (and this ended up being our kids' goals) trying to find as many "magic" photos as possible...and we/they found a bunch.
You then have the option of going online and "doctoring" your photos with borders, zooming, color-to-b&w, "stickers" and customizing to the proper size that you might later print (4x6, 5x7, 8x10) and making sure everything is exactly as you'd want it before printing. You can easily turn 100 photos into anywhere from 200 to 500 with different sizes, borders, etc., which further helps justify that cost. Sounds like I'm trying to talk you into it, but it's really up to you as to whether you think you would take enough photos in four days to justify it. We had an unusual summer in that we ended up going twice, and we were somehow able to manage the timing of downloads, etc., to get both trips on one MM, so for us, it was almost a no-brainer.
I will tell you that we were not able to download the Tower of Terror video. It showed up on our account, but never gave us the option to download it. Maybe that has changed (or will change) but unless you can get Disney (or someone else on these boards) to confirm a way to do that, it's neat to watch, but not something you can save. (For our own future trips, I hope this has changed...otherwise, I don't see much point in even having the video).
I don't recall how 1900 Park Fare does its photos, so I'm not much help there. I remember that, at one time, there was a place for pictures before you went into the restaurant, but I don't remember how formal it is and whether there is still even a PhotoPass photographer there.