Personally, i like the feedback. When you are working on an image, you can get so close to it that it takes a fresh set of eyes to point out flaws (the image i put up today is a good example. As soon as the flaws were mentioned I went, 'oh yeah... damn, i never noticed that.'). Other comments, even though they are just personal preferences being stated, can make you look at the image again even though you may not agree with the crit. Even if the viewer says your piece is shit... well at least you know who to take off your xmas card list.  Whatever the comment, it's all good.