It's a must watch episode of the series. There's a few that have to be seen but would serve as a poor introduction. This one and the Darmok one for sure.
Maybe someday! It's kind of a tough watch for me as it reminds me of a friend who passed away. I am ready to check out a few good standalone episodes though I think, which is progress :)
In recent memory I've gotten to explain the concept of Darmok a few times to friends that are either on the fence about starting, or had just started watching TNG. That episode is so goddamn strong.