Later seasons of Dexter (notably the infamous Season 8 finale and the revival Dexter: New Blood ) had their highs and lows. But stands alone as a complete, novelistic work. It set the template for the "prestige serial killer drama" that shows like Hannibal and You would later refine.
Season 1 answers these questions ambiguously. Harry is not a saint; he is a pragmatist who realized the system was flawed. By the finale, we understand that the Code is both Dexter’s salvation and his prison. Dexter Season 1