Typical disclaimer: this is just my opinion, but hear me out.
Mickey and Minnie's Runaway Railway is, perhaps, the closest we've had to a classic Disney ride since the 1990s. This is not to say that Avatar - Flight of Passage or Star Wars: Rise of the Resistance are bad in the slightest. They're both fantastic rides and also among Disney's greatest. But Mickey and Minnie's Runaway Railway is executed in the same fashion that classic Disney rides always have been executed in which they began in a real world setting and took you into a magical setting via some Disney magic. This is the element that makes attractions truly timeless and garner name recognition. You may find that many people who have NEVER been to a Disney park can still tell you what Haunted Mansion and Pirates of the Caribbean are. I believe that over the course of the next decade, with the ride confirmed to be opening in California and, prior to coronavirus, were rumored to be added into other resorts, we will find Runaway Railway to garner that name recognition.
I have noticed a lot of people are quick to compare Mickey and Minnie's Runaway Railway to Fantasyland dark rides and simply noting the attraction as an updated version of them. I suppose you could see it that way, but I think the much easier comparison is with Pirates of the Caribbean and Haunted Mansion in terms of execution and story-telling. Fantasyland dark rides took you into a new magical world but there's no real build up or continuity with reality. For example, in the case of Peter Pan's Flight, you simply sit in a pirate ship and fly off. There's nothing wrong with this approach and it is still, without a doubt, a classic Disney ride in its own right. But here's a break down of how Haunted Mansion and Pirates of the Caribbean approach the overall journey of the attraction and how Mickey and Minnie's Runaway Railway does so in a near identical fashion. And do note, I will be using the Disneyland version of Haunted Mansion and Pirates of the Caribbean as Walt Disney himself oversaw the development of these versions.
For Pirates of the Caribbean, your mundane setting is New Orleans. The journey begins as your boat leaves the station. You are in a swamp in New Orleans. A beautiful swamp. This is a real world location. Once you round the corner, the talking skull forebodes what lies ahead as you go down a drop into the caves below New Orleans for a glimpse all that is left from a world that once was. And finally, through that magical moment, the world comes back to as it was in the past as you enter in the ship battle scene. And after your glimpse into the past, your lift back up to the loading dock brings you back to the present day and the attraction has come full circle.
In the case of Haunted Mansion, the mundane setting is New Orleans but, to be a bit more specific, a seemingly abandoned house. The journey begins when you step through the front door of the mansion into the foyer. The ghost host forebodes what is to come with his narration (I must say, in Disney World, this element is done a bit better with the aging portrait). Unlike Pirates where the build up to the magical moment lasts for nearly half the ride, the magical moment that takes you into a new realm happens much sooner: when you enter the stretching room. (For clarification, I consider 'the magical moment' to be when what you're witnessing is no longer ordinary or mundane. Sure, swamps are beautiful and we don't see skeletons every day in the case of Pirates and the foyer and front lawn are spooky but the moment we leave the real world behind is the moment in which we see dead pirates come back to life and/or witness a haunted room stretch). After the ride through the 'realm of the supernatural' you exit your doom buggy and walk up and out of a crypt bringing the journey full circle.
And finally, for Disney World's latest addition, Mickey and Minnie's Runaway Railway begins in a mundane setting: Hollywood! At the Chinese Theater to be precise. You are headed to see the premiere of a new Mickey Mouse cartoon. You can make the case that the foreboding takes place in the song as Mickey and Minnie sing "we'll sing a song and absolutely nothing will go wrong!" The magical moment comes when the pie jams into the engine of the train causing an explosion and you step through the screen into the magical realm of a cartoon. After a wacky adventure, the journey comes full circle when you step back through the screen into the real world.
Mickey and Minnie's Runaway Railway, despite having one of the most brilliant executions in story I have ever seen in a Disney attraction, has been subjected to an avalanche of unfair criticism. Almost none of the criticism has much to do with the ride itself. Instead, opting to criticize the location of the ride and rationalizing that since it is a kid-friendly dark ride (Haunted Mansion is too guys...) it MUST belong in Fantasyland. Others are simply bitter that it replaced a charming, but hopelessly outdated attraction that lacked the whimsy and magic that a classic Disney ride has. And some others opt to criticize the animation style despite the fact that the classic style did not lend itself to the storyline of the attraction as well and (someone verify) the classic version of Mickey Mouse's animation's imminent entry into the public domain in 2024. The only genuine criticism of the ride is its reliance of screen technology but even that criticism is rather flimsy when you consider the fact that the ride utilizes this technology to the fullest extent. There is a scene at the end that transforms from a factory to a park in a stunning display of projection mapping technology and because this happens before your very eyes, it was not possible to do this with real life props. And that is where screen technology should be encouraged. I understand that screen technology has been used as a dodge in many instances; however, it is often used correctly and used for effects that cannot be replicated with real life sets.
Instead of trying to rip down the attraction, Mickey and Minnie's Runaway Railway should be embraced as a return to the roots of a classic Disney attraction. It was a formula that was laid out by Walt Disney himself and with Mickey and Minnie's Runaway Railway, was executed perfectly with his most beloved creation. An attraction that truly would have made him proud.