I don't think I've seen very many things scripted so well, much less any other farewell episode by any other show. It was great how it was a tearjerker in some scenes, but at the same time they would break through and make you laugh as hard as you would if it was any other episode.
Michael J. Fox's character goes out very gracefully, firing himself to save the rest of the staff. He then goes onto have some very sad (but also funny) goodbye scenes with each character in the show, essentially summing up his relationship with all of them. After Mike walks out of City Hall for the last time, he shows up in Washington, D.C. 6 weeks later as an environmental lobbyist. Throwing in a reference to his Family Ties character, Alex P. Keaton, there's also a feel good ending, and while the credits are rolling, he runs out to the bullpen, hugs each of the cast members, and waves goodbye to the audience.
An excellent fitting end to Michael's run on the show. Unfortunately, this was the last great episode, as the last 2 seasons never quite lived up to the first 4.