You will enjoy this more if you know a bit about the Royal National Theatre, such as that it was founded in 1963, and is one of the United Kingdom's most prominent publicly funded performing arts institutions. Many of the most well known British actors have appeared in its productions, which include dramas, comedies, classics, new plays and musicals. In 2009, the theatre began National Theatre Live (NT Live), a simulcast of live productions shown in cinemas, first in the United Kingdom and then internationally. In celebration of its 50 years of performances, this special event was put together and broadcast live as well, and is shown in the USA as a part of PBS' Great Performances.
The number of A-list actors and number of well-known plays this theatre featured at one time or another makes this show worth watching - you will find yourself saying more than once, "Wow, he/she was at the National Theatre? They did THAT play there?!." But that said, it was probably more satisfying watching this live, knowing that this was all happening in real time as you were watching, than it is to watch it recorded. The actors do a remarkable job of reaching emotional highs and creating compelling, honest moments in the snippets of plays they recreate from a variety of productions, however, you feel cheated when those brief moments end - just when you're getting into the characters and the moment, whoosh, it's over and we've moved on. Also, a few actors feel like they are just reciting something pretty, not really creating a moment.
If you love live theatre, or any of the actors featured, you will enjoy this. If you appreciate the history and grandeur of the National Theatre, you will enjoy this even more.