I couldn't agree with this guy more. It's so easy to criticize. Expressing criticism is something I've strived to work to do over the years. Before handing out criticism, I try to acknowledge and express appreciation of a positive attitude that this person has done. Expressing discontent first simply puts the person in a defensive position and I get myself nowhere.
I've heard that there is also a 3:1 ratio in terms of feedback. People will hear the one piece of critical negative feedback and internalize it if you have also told them 3 positive things