It does sound rough, but when it comes to art, especially drawing, not telling the artist what you really feel about their work is doing them a massive disservice. In the end you want your art to be seen, and you need to express your imagination in a way that can reach people. For that you need to know how they feel about it, and most will never tell you.
Criticism should always be constructive, but should never ever be soft.
I got some background in art (stuck somewhere between psychology and serial arson) so I do want to go in depth with the pointers now that I know the thread's active.
Gonna take a bit.