I don’t like Myers-Briggs tests. People make them look scientific and use scientific wording but they aren’t based in science. They don’t promote self-reflection any more than a horoscope. Most of all, they imply that you don’t change much, a belief that discourages personal growth and exploring and using different skills for different situations.
People who believe in Myers-Briggs tests say things like,

“I’m an ESTJ [or whatever], so I act like [how Myers-Briggs says they’re supposed to act] and work well with [whomever Myers-Briggs says they’re supposed to work well with], but not [whomever Myers-Briggs says they’re not supposed to work well with]”

and then they follow along without challenging themselves or exploring their boundaries, resulting in them stagnating.
My experience with my own and others’ personal and professional development contradicts their implication. I think the less exposure people have to Myers-Briggs, the more they’ll be able to change parts of themselves they want to change.
Regarding how it tells you something about you now, people tell me it helps managers staff teams. They point out that even if you change later, for a team to work now, it helps to know a team’s members’ working styles now, to staff the team optimally. While I question how one’s responses to a test correlate with behavior in different environments any greater than a horoscope, even if I grant that correlation, that information helps your manager more than it helps you. To some extent it helps team members, but I don’t see how much it helps more than their simply observing each other.
In the meantime, the Myers-Briggs basic belief holds you back from personal development and developing skills to solve problems you can’t solve now.
I find the “Origins” and “Criticism” sections of the Myers-Briggs Type Indicator Wikipedia page helpful to put the test in context.