While no one has leaked what they have seen, Grace Randoplh, who gets insider info from the movie industry through multiple sources, has gotten wind that the test screenings for Transformers One have gone "extraordinarily well". That means those who saw it responded very well to it. This is great news, since while the film may not be every fan's cup of tea, it does mean that families, the target audience, will more than likely enjoy the film. And we'll see if that translates to box office gold or not. In any case, this is an encouraging development in this phase of our beloved brand.
Grace mentioned the test screenings in her video discussing Chris Hemsworth's probable casting in the upcoming GI Joe/Transformers crossover film.