A very interesting opinion from Mike Johnston :
A bit of encouragement or constructive criticism, goes a long way. I’ve had personal experiences where I have once been at the receiving end of very negative criticism for various reasons in the open source project that i contribute to. And such incident(s) does impact ones self-confidence. Being sensitive to others feelings, tolerance and words of encouragement do make a lot of difference.
Somebody once told me, If you have nothing good to say, then don’t say anything. And I can’t help but agree.