I find that criticism, be it constructive or even destructive, is always tough to take. I struggle with this on a day to day basis even to this day. Destructive is just that - but constructive, when from a reputable source, can be invaluable to the writer if he/she takes the time to take it into consideration.
I think the key is to separate the dinstinction between the criticism making a personal attack on you vs. the work. The person giving the criticism doesn't personally know you, so taking something personally is probably the wrong course of action. Rather, if you focus on the criticism being a reflection of the work, you can use it that information to help you write better in the future and identify areas in your writing skills that need improvement.
In seems that having "thick skin" as John puts it is an asset to nearly any profession.