So... I did the thing. Here's my opinion:
The Queue:
Entering the Chinese Theater was like a walk down memory lane. The original queue up until the preshow was beautifully intact and still includes the digital movie poster displays. The preshow is fantastic! As many people have mentioned, the effect of walking into the screen happens in a very unexpected manner and is sure to impress. I seriously geeked out over it! The station is nice. You definitely see the ghost of GMR hidden in its layout.
The ride:
I honestly had a lot of fun. It's like a fantasyland dark ride gone E-ticket. I was EXTREMELY impressed by the projection effects. Unlike Ratatouille, the floors didn't distract from the projections for me. The animatronics are largely unimpressive. Mickey and Minnie in particular just looked really... off. I would suggest not including the projection faces in the future iterations of this ride as they are my least favorite attempt at implementing this technology. The story was definitely done in the style of the new Mickey Shorts. It was very fast paced and immersed you in an environment that overloads your senses. I personally feel that the chaos detracts from the ride's storytelling, but what it lacks in its ability to hold a rider's attention, it makes up for with all the fun that is going on in the background. One of my favorite moments is one of the simplest- when you encounter Daisy Duck. The finale is cute, but nothing fantastic. The original song is quite fun and, after a few rides, will likely be stuck in your head. The ride exit is the nice little bow to tie everything together - It wasn't necessarily, but it was such a nice touch!
I'd grade MMRR as a solid B+
This ride was overall very well-executed and was a lot of fun! Judging it solely on its existence as a Disney ride, I think it's a very strong addition to a park that is lacking in family rides. The whole family will enjoy riding this together. I frequently caught myself smiling and laughing while the child-like grin never left my face. The projections are over-the-top and unlike anything I've ever seen on previous rides. I honestly never thought I'd enjoy a projection-heavy ride this much!
Does it compare to GMR? No. Why would it? It's a completely different type of ride from GMR. My heart will forever have a hole left in it from that ride's removal. Was MMRR a star in its own right? Absolutely. They just should have never put it inside this building in the first place.