There are some hourly Attractions CM's that have taken multiple test rides on Nemo, as well as the salaried Tomorrowland Attractions managers. The word back from them is "I can't say anything, but.... OH....... MY........ GAWD is it a good ride!"
But until the state inspectors from DOSH show up and approve the facility after a week of inspections and tests, only Disney Company employees are legally allowed on the ride. And of the DisCo employees, about the only two groups allowed on are Imagineers and Attractions CM's. And some Burbank or senior TDA execs like Bob Iger, John Lasseter, Ed Grier, Greg Emmer, etc. Iger and Lasseter have been visiting Anaheim regularly lately, and the lagoon is always a stop on the tour.