What are the advantages and disadvantages of using facial expressions when communicating?

Advantages:

• People see your emotion by your facial expression.
• Can show if you are happy/sad, satisfied/unsatisfied, angry/pleased etc without saying a Word or while other is talking with you.
• It can make you know if the conversation is boring or interesting by the people's face expression.

Disadvantages:

• Someone can feel offended or insulted if you made a negative face expression.