Introvered vs Extroverted is probably the most rock-solid part of MBTI. However, psychologists are using the terms in a very strict sense, removed from the connotations we normally attach to the terms. Specifically, it's if you take your energy from inside or outside. Under this definition, introverts can get along with people just fine. It's just that they tend to get worn out being with groups for long periods of time and have no problem working alone. They may choose to be with people, but have little psychological need to be with people.
The other three measures I'm less sure about. While people often feel their personality descriptions are very close to how their actual personality, you can get the same effect using cold reading/Barnum Statements. It's not clearly better than fortune telling.
"There is no shame in being self-taught, only in not trying to learn in the first place." -- Atrus, Myst: The Book of D'ni.