To be honest, I loved the meditative structure of the film, which the extended scene in the apartment is incredibly representative of. It took itself at a steady pace (one could say it was indulgent in that regard, but if so, then it earned that indulgence coming off of the good graces of the series) and was introspective in a way that the show couldn't really be just by the nature of its structure. The apartment and the length of time we spent there allowed us to spend a lot of time with Jesse as he figured out his situation at hand and came to terms with his current mental and emotional state. It was in the apartment, I think, where he decided that he had a chance, and that he wanted to live.
To echo something that Vince Gilligan said in a recent interview, El Camino was in no way necessary. You don't need it to appreciate or understand or get a sense of closure from Felina. What El Camino is, at its heart, is an epilogue providing emotional closure for a character that we've come to love and appreciate as the moral center of the series (and, at the same time, an excuse for Gilligan to indulge in his Western fantasies yet again). In some ways it is a structurally lot like the episode Fly, and if you ask me that is a very, very good thing.
