Critique is the most useful thing, but a very delicate one. It should be used with care. It is absolutely different from comments. Comments are kind of promotion, we should keep them favorable and seen by everyone, while critical notes can be offencive or valuable first of all for the artists, they are not for possible customers and collectors.. I think we should always separate critique from comments. Probably the best way to get critique,, which you need, is to start a thread at this discussion board. Here you can ask others for critique of a certain picture, ask for general help or to ask any specific art question.