Alright, I have officially ridden the attraction and have a lot of thoughts. Not sure how novel any of this is because the page count of this thread jumped by 70+ pages since I ducked out to avoid spoilers so I apologize for retreading any ground.
Where to begin? Perhaps a goods vs bads to lay everything out and then some final thoughts. I would also like to state that I was coming into the ride with moderate expectations leaning positive and attempted to view the attraction on its own merits separate from its history as Splash Mountain (but then found that harder and harder to commit to).
The queue is nice and I quite enjoy the radio loop playing. The radio in particular gives a vibe that a tiny slice of New Orleans Square has come to WDW and does a good job at establishing Tiana as an important public figure. I absolutely love the lush greenery of the interior sets and dark lighting. The critter bands are very cute and add a great bit of liveliness to the spots they appear. The A1000s of Tiana and Louis are all a treat to see in full motion. Upon first hearing the rumors that there would be a shrinking/transformation portion to the ride I was highly skeptical it would be a good choice, but I think it turned out well and was a fun way to display the animatronic frogs much larger, as well as call back to the film. The primary thing to praise here is the finale scene and original song. The energy in that scene is great and really delivers the most complete part of the experience.
I generally don’t think the screens in this ride are too egregious or overbearing - they are actually quite minimal - but the shot of giant Tiana and Louis looking at the riders in the shrunken portion is the worst visual offender of the ride. It genuinely feels out of place and their dialogue could have been delivered with audio only to convey the same thing. As many have mentioned, there are quite a few empty stretches along the ride between characters. Not every ride has to be filled with animatronics to be good, and not every animated figure has to have complex motion to be effective at conveying what it needs to, but there is still a lot to be desired from the emptier scenes. The space between the 2nd band and the transformation dip drop is particularly empty, so much so that while on the ride you just instinctively look to watch the boat ahead of you complete the dialogue with Tiana right before the dip drop, only to immediately hear it again directed at your own boat. Though the A1000s are lovely, they are mainly used to just look at the ride vehicles and gesture at things. The finale is the only scene where it feels like the any A1000s are actually doing something within the narrative like dancing or playing music. Perhaps the greatest flaw of the ride though is that it lacks any poignant stakes, dramatic tension, or low beats. When designing a linear narrative experience a writer will typically create a graph laying out where the emotional high and low points of a story will be so they can fluctuate in a logical and satisfying manner. It feels to me that if you were to make something like that for this attraction it would be super flat and monotone with a lone spike at the finale. And while it’s true that not every attraction needs a well executed narrative or complex emotional arc to be really good, the issue lies in the nature of the attraction being a replacement.
I really tried to let this ride live on its own merits separate from Splash Mountain, but the positive elements of this ride come at the expense of another attraction, and they extract a heavy toll. Tiana’s Bayou Adventure is by no means a bad attraction and far from the worst retheme in WDW, but it does not live up to the narrative, emotional stakes, and technical feats of its predecessor. It’s very much like Runaway Railway in that sense; it’s quite enjoyable and a decent ride on its own, but it should not have been a replacement in a park desperate for additional ride-through capacity. Even with the social issues surrounding Splash Mountain and Song of the South, there could have been tactful methods of updating the plot and concept with different characters to deliver the same strengths of the experience.
TL;DR: Don’t give in to the hysterics of people saying this is the worst attraction WDI has ever produced because it is a decent ride; but it does not evoke the spectacle of its predecessor, making it hard to enjoy for those that know what came before.
A couple notes and addendums to my initial review after viewing some POVs and further rumination:
I was originally displeased with the lull section between the 2nd critter band scene and the scene before the dip drop for being too empty compared to Splash, but I'm beginning to realize this is supposed to be an intentional "low moment" in the narrative before the shrinking scene. The primary thing that suggests this is the lower-tempo audio loop next to the wooden shack. I think this actually a good spot to put a short atmospheric section (Splash did this as well) but I'm not sure it's the best execution. In this spot, my eye was instinctively drawn to the Tiana animatronic further down the flume as it's delivering dialogue to the boat ahead. The audio bleed from that dialogue stole my attention and I missed the ambient audio cue. Something more than the wooden shack to draw the eye to the left side of the track would do greatly for this scene. Just after the segment of Tiana sitting on the stump and Louis looking in the log, we see some stationary figures of the frogs before the Mama Odie screen and dip drop. I know the frogs are there to kind of foreshadow the next scene, but I think they would be better utilized just after the wooden shack in the ambient section. I overlooked the static figures there on my first ride because they were competing for attention with Mama Odie, but putting them just after the shack would allow the Tiana and Louis figures to move further back into their scene and create a better flowing sightline in my opinion. This is all sounding very nitpicky though.
The section between the first and second bands is meant to be a small "scene" where we follow the line of fireflies. There is an effect of fireflies flowing in a line depicted on the leafy canopy ceiling with fiber-optic lights. This is a really great effect, but the scene also suffers in execution because it competes with the screen at the far wall; which is more likely to grab your attention and leave the sides of the boat feeling rather empty. It would have been nice to see this fiber-optic effect on the sides of the flume, and maybe even have it weave around some additional critters. Again, a bit nitpicky.
Regarding audio, I'm now aware that several characters have variations on their dialogue to make audio bleed issues less awkward. This isn't something I picked up on during my first ride, but it's a nice touch nonetheless.
I do not understand the criticism from many that the plot of the ride is complicated or hard to understand. I understand why some might find the queue backstory hard to grasp (while I personally disagree) but the on-ride plot is incredibly simple and easy to follow. The first lift hill Tiana blatantly states she is looking for musicians to play at her party, and Louis in the garden does the same. Before the former slippin' falls drop an audio cue of Mama Odie states we can find the musicians in the bayou. Then, each following appearance of Tiana and Louis reiterate that the musicians they find will be joining them at the party. I can see why the shrinking dialogue from Mama Odie might be hard to hear and understand, but this is immediately followed by visuals of a giant bottle, key, and frog to suggest we shrunk. Then Mama Odie explains she will grow us again so we can make it to the party, all while the vehicle is stopped at the bottom of the main lift hill. Her animatronic at the top of the lift reiterates we're going to the party, and then after the drop we actually go there, completing the plot. If anything, I think the dialogue is heavy-handed and feels somewhat childish, but that doesn't bother me nearly as much as I thought it would. Clearly the dialogue wasn't dumbed down enough for some!
Even though on the whole I prefer Splash Mountain as an attraction, I think it's disingenuous and in bad-faith to call Tiana's Bayou Adventure "soulless" as many have jumped to claim. While the direct plot of the ride is very simple to appeal to younger demographics, there is a surprising amount of subtext here. The attraction feels like a love letter to New Orleans and Louisiana as a whole. The different critter bands playing different styles of music pioneered by African-American artists represents bringing different people in a community together to create something no single person could have created themselves. This parallels the inception of jazz music, which many consider to be the heart and soul of New Orleans. The original song Special Spice also draws this as a parallel to New Orleans cuisine (also considered the city's heart and soul) which uses an eclectic array of ingredients to create its unique flavor. The ride is showing the creative intersection between the culinary and musical arts in a city prolific for both. It drives home that creating something alongside others will result in something none of the parties involved would have ever created on their own. Many are quick to say this ride feels like it was designed by committee, but it seems clear to me that was deliberately the intention. Whether or not one prefers that approach is entirely subject to opinion, but it's not devoid of character or clever design.