Michael Scott sets himself an ambitious challenge in "The Secrets of the Immortal Nicholas Flamel": cramming a sprawling story with twists and turns into just six books. The result is a remarkably well-constructed series. 

Scott masterfully weaves together a main plot with subplots, historical figures, and mythological elements. The world-building is fantastic, seamlessly blending folklore and legends with fantasy. He breathes new life into historical figures,giving them pivotal roles in a modern-day conflict. 

A refreshing change from the norm, this series avoids romantic entanglements for the protagonists. Instead, the focus is on compelling character development. We witness characters switch sides, grapple with internal struggles, and forge strong bonds. The dialogue is both humorous (especially between Scathach and Shakespeare) and poignant. Dr. John Dee is a complex antagonist who evokes both hatred and grudging respect. The new villains are shrouded in secrecy, further fueling the intrigue. 

This series excels as a mythology lesson, introducing a rich tapestry of characters and lore that inspires further exploration. From the Four Elemental Swords to Danu Talis and Hekate, there's so much to discover. 

The eye-catching covers perfectly complement the story's themes. Each cover represents an element and features a character – silver for Sophie and gold for Josh. The artist behind these visuals deserves high praise. 

The ending is mostly satisfying, leaving a few questions unanswered to potentially set the stage for the "Earthlords" series. The action sequences leading to the climax are fast-paced and well-written, showcasing a variety of verbs that could enrich your own writing. While the conclusion feels slightly rushed, it's a happy and resolved ending that leaves you eager for more. 

Overall, "The Secrets of the Immortal Nicholas Flamel" is a captivating series with strong characters, a rich world, and a compelling story. Fans who enjoy mythology and fantasy will find much to love here.