I'm sure there are books about How To Create A Television Pilot, and this episode will probably be featured in it. The difficulty with an ensemble piece is that you only have twenty minutes to introduce several characters. The writers have come up with clever device here: a broken pay phone gives everybody a chance to phone a loved one. (By sheer coincidence I happened to see "Hell is For Heroes" the day before, in which Bob Newhart does a long, one-sided phone call. Apparently, it's a situation that comedians have used for laughs a long time.)
With just a few lines each we get a good idea of what the different characters are like. The writers could have introduced them in the classic way, as both John and Elaine start their jobs at Sunshine Cabs. But that would have overwhelmed the viewers with information. The background stories of both John and Latka are not given; their actions suggest their personalities. Danny DeVito was relatively unknown by then, and one of the biggest laughs comes when Louie steps out of his cage and the audience first notices DeVito's size. I wonder whether that would still be acceptable now.
In the last five minutes the show's seventies roots become apparent. We get a rather sentimental scene, with Alex looking up his estranged daughter. Perhaps this sentimentality was par for the course in the seventies, perhaps it was just used to stress that Alex would be the lead in the show. Anyway, it's the element that feels the most dated.