Monster is incredibly overhyped. There is some charm to be had here and there but the characters are not believable, plot points get repeated constantly til your ears bleed, and the writing is overall very simplistic and cliché.
The only reason I managed to finish it is because I was watching an episode or two while eating or while too sick to watch something good which requires focus, and I kept hoping that the ending would be good and redeem the show, but unfortunately I was finally let down months after I started it.
There is some charm in that the characters eat almost every episode(watching characters eat is cool, ok?), the setting and era is nice. But none of that can carry the show.
The plot had much potential, and if it had a better ending or more believable writing throughout the show it could have been great.
If you don't like it after 20 episodes you won't like it after 74.