I'm not saying it's ok to criticize a director just off a trailer, but I do think it's absolutely fair to critique a trailer's style based on what is being seen. More than that, isn't that what trailers are for????
A trailer is an ad for what's to come. If someone sees something they think doesn't look right, or is 'unpleasing to the eye' they have every right to say what's on their mind. Even more so, the viewer is the person who eventually coughs up the $$ to see these films.
Film is art...art gets discussed and criticized.
EDIT: I should have said discuss away...not judge. My bad.