I don't think it's an E ticket (though any opinion on that would be just that, given that ticketed rides no longer exist) simply because, like
@voodoo321 said, it's just a shuttle from video screen to video screen with a few oversized props. That's not really sophisticated. The only thing that is really high-tech is the trackless ride system, but Universe of Energy had an early version of that in 1983 and
MK has had that in Pooh for years (I was mistaken. See below.). Will it be successful? Of course. People love Ratatouille and it swallows a lot of people at once, making it something that, in theory, shouldn't have crazy waits. It will be fine. It's not a classic for the ages, but won't be a load of mouse poo, either. Definite C-ticket, in my opinion.