Despite having only the most basic of story-lines, this is a nicely-crafted movie with a worthwhile story. Ernest Borgnine deserves the praise he has received for his performance as "Marty", and he seems very natural in the part, for all that it seems so different from most of his other roles. The other characters are also rendered believably, and events develop naturally. While the two main characters may think of themselves as failures, viewers can see that they are just ordinary persons trying to be honest and sensitive, and this makes it easy to identify with them.
The story efficiently introduces Marty and the other characters, showing how he interacts with them. Since the others are all so absorbed in their own concerns, they view Marty solely in terms of how he fits in with their own plans and desires, again making it easy for the viewer to relate to him. Joe Mantell, Esther Minciotti, Augusta Ciolli, and Jerry Paris make Marty's family and friends thoroughly believable, and they work well in their interactions with Borgnine. By the time that Marty meets Clara (Betsy Blair), everything is set up so as to get the most out of the possibilities.
Praise also goes to Delbert Mann and Paddy Chayefsky for being willing to make a movie out of such low-key material. It may not impress those who have become benumbed by the ostentation of present-day film-makers, since its quality is of a subtler, more unaffected kind. But it's a worthwhile achievement in its own right, a story about ordinary persons and everyday concerns, of the kind that takes skill and understanding to make well.