Meet-up as the name implies is a simple gathering of people.
In my case commonly family and friends as my tag goes #steemfandf .
STEEMIT Meet-ups encourages people to express themselves, be free, ask questions, get to know each other more.
Now meet-ups could be planned, like with a fixed date and schedule of the activity and what not, or they could just happen and those are the ones that really bring out the steemian in you.
I personally like spontaneous meet- ups because you catch the people where they are comfortable and they say out their minds.
Though preplanned meet-ups are good too, as people get time to go deeper into questions and think deeper too based on other people's responses.
Overall I think meet-ups are good, for the STEEMIT community promotion and for individual growth and unism.