I typically don't give reviews for individual episodes of shows. But, when looking through IMDB's highest ranked episodes of DBZ, I found that this episode was ranked number 275 of 277. Why was this episode ranked so low? I didn't think it was divisive episode, everyone I have spoken to about the show marks this as one of, if not, the best episode of the show. I will personally take it one step further. Not only is this the best episode of Dragon Ball Z, this is one of the best episodes of any TV show EVER.
This episode felt like the culmination of everything DBZ was building up to. It gives such a good sense of closure; it is no wonder that both DBZ Abridged and DBZ Kai ended their runs after this episode. "Dragon Ball" was the story of Goku rising up and gaining the title of "strongest under the heavens", "Dragon Ball Z" felt more like the story of his son Gohan. They introduce Gohan in the first episode of the series. Throughout his journey there were different sparks of brilliance, where people could see that there was something more to this kid. The show wisely never had him strong enough to just flat out defeat the enemies, but the strength was there. Against Raditz, Nappa, Recoome, Ginyu and Freiza you would see these little glimpses of Gohan's strength but never having him just solve the problem on his own. (Unless you count Garlic Jr.) Point is, this is the blueprint of how to do an "untapped potential" story. After nearly 200 episodes of buildup, this is the payoff.
Cell is also the, (forgive the pun) perfect villain for the series. He is an amalgamation of all that has come before him. The strengths of all the strongest fighters put together in one. He is also a good carry over from a conflict introduced during the "Red Ribbon Army" saga.
On top of all that, this episode provides closure for a lot of the other characters. Piccolo, Krillin, Tien, Yamcha and especially Vegeta, all get a time to shine in this episode.
What more can I say? It is a PERFECT ending.