I always describe it this way...
Its like watching Star Wars and the movie just ends as the Death Star arrives at Yavin. The ride is a great buildup for an epic ending that never happens. You get this gorgeous story of the Navi coming together for a great musical celebration. The forest begins to come alive with movement and music, you turn a corner and see the Shaman singing and inviting you to join the celebration, you then enter...a virtually empty room, then you get off the ride.
Honestly, if they had that stupid last room filled with AAs, screens, movement and music, it would be a classic. As it stands, it feels like a story that that rises to nothing and is actually more disappointing than if they just didn't have a story.