Don't bother to sugar coat your comments, or to consider the artist's feeling when reviewing their work! It might be the best I've seen, I tend to live by the motto that any comments/feedback should be in a language that I'd want to receive.
In regards to the user "Just"'s 'critique' he is free to critique art as he feels, either sugar coating it, or substituting the sugar with lack of eloquence and actual feedback.
In regards to your response, you have to understand that art critique is not intended to make an artist feel good about their work. The purpose is to weed out the artists from the non-artists. Meaning, that a strong critique is taken for what it is by the artist seeking to advance in their work, while the non-artist with a modicum of technique and skill [yet, lacking subject or composition] takes it personally and becomes emotional. The purpose of art critique is to help an aspiring artist evolve, "molly-coddling" an aspiring artist is detrimental to their evolution and creativity as artists and in general to their psyche as a human being.
Growing up, when I attended art school and classes and other programs, the critiques were harsh. Many students cried, few could handle them emotionally and eventually gave up either striving to become better or altogether. The few that persevered are those that were not fazed by the words but who embraced them in order to reflect on why they received such harsh criticisms.
As for the OP's work, then no, the hand does not look real in the least. As "Just" has stated, it has [black] outlines that do not exist on the human form. The hand is a cartoon representation of a human hand, and there is nothing wrong with this if the work is intended to be a cartoonish.
Also, for the OP, I do not think they should get much ahead of themselves, at this level at least, and begin to make tutorials. Rather, focus on honing your technique and skill if you are striving for realism, but if this is specifically a personal style you want to teach, then, continue what you are doing, and do not listen to me or anyone.