It enhances the series by adding more content. Simple as that. More stories mean more gameplay time and more things to discover about the Arkham world.
Probably. The Arkham series has a connected storyline, and it would make sense for the Arkham Knight new story to be a continuation. This way, it can keep the lore consistent and develop the characters further. For example, we might see how Batman has changed since the last encounter with his foes.
One interesting aspect is the expansion of the Arkham City universe. It allows players to delve deeper into the lore and characters. For example, we get to see more of the relationships between Batman and his rogues gallery. Also, the stories often introduce new challenges and puzzles for Batman to overcome, which adds to the overall gameplay experience.
One of the most popular is also 'The Shadow over Innsmouth'. It has a great story that unfolds gradually, revealing the secrets of the strange town of Innsmouth. The themes of isolation and the unknown are really well - explored here.
The 'Arkham Asylum: A Serious House on Serious Earth' is often considered one of the best Arkham stories. It's a dark and psychological take on the Batman universe, exploring the insanity within Arkham's walls. The art is gritty and really sets the mood for the story.