Complain privately. Compliment publicly.

Show people some respect! Compliments work best with an audience because it multiplies the positive effect of bein complimented.

Complain on the other hand does not work at all with an audience involved. If you complain so someone in public he thinks about the humiliation and his social situation but not about the essence of the critique. Complain in private and in a nice tone on the contrary and he can make the best of your complaints.

Show some greatness, do it the right way!

/phil