As far as I am concerned, the plotting was well set perhaps bringing out the powerful theme of how the 'silly spell of American dreams' could result to a downfall especially in the garden of male friendship. Also no matter how closely pure and mutual you are with each other, evil can be found in this world in some possible way.
The plot is adequate and compelling, as far as my opinion goes. This was a hybrid work of fiction where Steinbeck set out to create a book that was part dramatic form and part prose fiction.
I think he achieves his aim remarkably well in Of Mice and Men, in a way that is more artful and less political than The Moon is Down.
The plot here does its job. The conflicts are clearly defined and multiple, though not overly simple or predictable.
The plot is rather repetitive and circular with the first and last chapters having a similar beginning. The simple plot effectively demonstrates the endless cycle of George and Lennie--they continually go from ranch to ranch hoping to find their dream. The slim plot reflects the simplicity of George's and Lennie's lives. They will never get ahead and they will always be working men. The plot is simple, but the ideas and themes that Steinbeck conveys are timeless and universal.
John Steinbeck, who wrote his novella, Of Mice and Men, with the idea of its being made into a play, was himself surprised at the reception that it received. But, what makes such a striking impression about this novella is its powerful existential theme of man's aloneness and alienation and the Naturalistic treatment of this theme. For, in a slim,Steinbeck shockingly reveals the resulting cruelty and violence that develops in men from their sense of alienation. Indeed, we see this result in our own dehumanized, alienated society today, do we not?
The plot isn't complex. that's for sure. That may be translated as simple but probably not slim. The characters are recognizable and memorable, which means however you might describe the story, it is effective. The George and Lennie characters are recognizable in lots of places, including cartoons and movies. (Think Foghorn Leghorn and the chickenhawk in Loony Tunes.) I agree, though there are several major, shocking happenings in the novella, this is a story about the people more than the action.
I don't think that there is much to the plot. You could sum up the important plot points in two or three sentences.
However, I do not think that we can really criticize the book for that. First of all, it is a very short book that cannot really have much of a plot (there's not time for one). Second, and more importantly, the book is not really about plot, in my opinion. To me, it is more about the characters and how they are fleshed out by things that would not really count as plot.