We ate there for dinner Oct. 2006. We are not fond of buffets for dinner, but booked this since they did not charge a premium for the Fantasmic dinner package. DH, DDs and I enjoyed it much more than we expected. We did not notice any cleanliness issues, and the bathrooms are shared with the restaurant next door (50's Primetime, I think), so they were clean. All in all, a good experience.
(The main reason we picked it was for the Fantasmic package - since F could be canceled due to weather, we didn't want to pay extra for the seats and then not get to use them. I don't know if the price is the same now or not, but it is definitely something to think about!)