Depending on who you ask, Del Close was either an unrecognized pioneer of long form improv or a guy with drug and alcohol issues, who was extremely hard to work with. Thank You Del tries its best to provide a balanced opening on Del Close, even though the film's focus on the Del Close Marathon does cause the opinions to lean towards the overwhelmingly positive. The film features performances and interviews with those involved with the event, such as Amy Poehler and Matt Besser, as well as an upstart improv troupe from Missouri named "Hi, Let's Be Friends."
While it would have been nice if Thank You Del went into more detail on those Del Close influenced, such as Bill Murray, the film does feature many incredibly funny improv performances. In fact, Thank You Del is not far off than being a full-on performance film, which just happened to also include some background information on Del Close's life.