In my own view criticism is not only a fact of life that we writers and authors live with, but also a potentially very valuable tool for improving the written piece and the skill of the writer.
There is emphasis on the word "potentially." While much has been written on the ill effects of destructive, acid criticism and the danger of responding to ill-informed, ill-advised criticism, the writer can do much to mitigate these effects and this danger by becoming their work's first critic.
To do so effectively first requires a change of mind set--it requires one to view their work as a piece of work. There is a certain amount of emotional detachment necessary, but rather than detach completely from the work, the writer has to attach himself or herself to it in a different way.
To be an effective first critic also requires an understanding of where the work is in the writing process (and so understanding the process itself), what are the appropriate questions to ask, and how best to ask those questions to identify areas for development or improvement.
When writers become their own first critics, they have tremendous power and influence over their writing. The key, as written above, is to become an effective first critic--one who's criticism leads to a more empowered writer and a more powerful piece of writing.