Taste in artwork (and photography is a form of art) is personal and what one person percieves as "ordinary" another person might think of as brilliant.
Somehow I get the feeling that you want justification for providing negative feedback Leon? I know that when I post in the terrestrial section I don't seek approval that my photo is great, and I don't seek advice on what is wrong with it (unless I was to specifically ask for feedback). Sometimes I just want to share.
If this is in relation to the sunrise pic, the OP clearly states that critique is welcome, so I don't see any issue with providing a personal opinion, even if it is negative. Personally, I think that pic is brilliant!