In Season 1 ST Enterprise introduces the characters, the beginnings of Enterprise and its mandate. It was the beginning.
Season 2 is a bridge to the seasons to follow: The natural evolution for a series is met in ST Enterprise Season 2, which is character driven: It fully develops the characters and the relationships between them, their hopes, dreams. Their banter, friendly disagreements, their playful sides, their common goals make this an interesting character-driven season, allowing the audience to easily relate to all of the characters by the end of Season 2.
Without having the maverick, yet steady as he goes captain who puts his crew first; the interfering, condescending Vulcans who really do know best for having walked that road; the break-the-mold loyal Vulcan second in command who is for humans/against humans, according to the situation; the easy-going, down-homsey engineer who jumps in without thinking, yet who can use his superior intellect to build anything and solve problems; the skittish, yet one who can be brave communications engineer; the loner arms officer, who begins to feel like he has a family in the crew of Enterprise; the confident highly knowledgeable doctor whose insatiable curiosity is constantly being assuaged and surprised by humans - without all of these conflicted characters there could not have been the Season 3 to follow.
Season 2 - The Bridge - successfully did the job it needed to do! It had good plotting, but not the great plotting to follow in Season 3. Season 2 had brief plots which disclosed how characters would act under various circumstances. Laying the groundwork of fully-developed characters and how they react under given circumstances in Season 2, allowed the writers both freedom and preparedness to develop a fully plot-driven Season 3.
Season 2 works.