The Myers-Briggs Type Indicator® (MBTI®) instrument is a questionnaire designed to make Carl Jung’s ideas about psychological type useful in everyday life. It identifies a person’s four basic type preferences that combine into one of 16 different personality types. These results help you understand normal differences in the way people think, communicate, and interact—differences that can be the source of much misunderstanding.
On the MBTI notion, it is unethical to use the MBTI for the selection process or in promotion interviews and considerations. It is unethical to make those type of judgments based on the instrument. The MBTI is only used to help people understand the different communication/personality styles. It does not tell people their type. Everyone can be any type they want. One of the best things is its assumption that all 16 types are good. The types are strictly defined as "preferences."
Many "mainstream" psychologists find faults with the instrument; however, they are the same ones promoting other instruments. One of the knocks I have on the MBTI is in the area of Reliability and Validity. Thousands of research projects give the instrument excellent standing on these two important aspects; however, I noticed most are done by the Publisher of the test, or someone the publisher financed, or the Association on Personality Type. So, it could be a valid concern. However, critics have not done studies with findings one way or the other, they simply point out the flaws.
Besides, if people can pick their type and it makes them feel good, what is really wrong with that? I don't agree with some of the pop psychology out there today; however, if it makes people feel good, and they change their lives for the better, who am I to be critical?