Yeah I was a little mean but I don't owe the dev an extremely polite, toothless review when the demo I played was loud, annoying and gave me a headache from the FOV. He isn't going to shatter into a million pieces.
Well, as a dev working on a similar game, criticisms from people who want you to improve are useful, as long as they are precise and give fairly clear directions. Like saying "this is bad" isn't helpful, it doesn't tell what I could do to make it better.