We rode the Little Mermaid ride and used the wheelchair accessible car each time.
Queue:
Is wide and mostly level. The ground is concrete, stamped with small bird footprints and has shells and small fish/aquatic creature skeletons embedded in the concrete. This did not seem to make it bumpy or noticeably uneven.
The early parts of the queue are divided by half walls of 'rock' , but are fairly open.
As you get farther into the line, there are full walls on the outer sides and a ceiling made of 'rock'. All of the hard surfaces means that the area is quite noisy and echo-y. The final several rooms of the attraction all have walls and ceilings. (I will post some pictures on another thread later).
It was not clear in the preview exactly where the Fastpass line would go, but it appeared that line would share the last few rooms with the regular queue, so sound would probably be similar.
There was also music in the queue, which can be loud. People with sensitively to noise may want to wear ear protectors for this.
Loading:
I rode both times with DD with her wheelchair. Guests with mobility devices go thru the regular line until the point of boarding. At that time, those guests are routed to the exit to wait. The waiting area is roped off from the regular exit area and is wide enough for several mobility devices. It is long, so they could have a fairly large number of guests waiting there.
Wheelchairs and
ECVs for guests who are transferring from their mobility device will be stored there while they ride.
There is a moving walkway, which is quite long, allowing for a lot of time to transfer into a ride vehicle. The CMs had no problem getting DD's wheelchair loaded and unloaded without stopping or slowing the walkway either time we rode.
Accessible ride vehicle:
There is a dedicated wheelchair accessible clamshell. The ramp folds down from the back of the clamshell. The CMs seemed to have no problem with this the times we rode.
The companion is directed to get into the clamshell first and sit on the seat on the left side. The wheelchair is pushed up the ramp and aboard by a CM. The ramp was not overly steep and there were no impediments of things I could see that would stick out and prevent some wheelchairs from fitting. DD's wheelchair is a narrow adult wheelchair and we had plenty of room.
Backpacks must be removed (this was a requirement for all accessible ride cars we went on - I think they may have had some difficulty with wheelchairs tipping because of the weight of the backpack).
There is a shared seatbelt with a plastic slide connector. Squeeze on the sides to release.
The ride:
The ride itself was cute and tells the story of the Little Mermaid. The audio was fairly loud, so people with sensitivity to noise may want to wear ear protectors for this one.
The ride car turns to face each scene and the turns were sometimes a bit of a slight jerk. Not painful, but noticeable.
I'll write more about the ride itself in a separate thread.
Unloading:
Very similar to loading. The CM opens the ramp and brings the wheelchair down the ramp. Then the companion gets off and takes over the wheelchair to go out the exit.