I'm nearing the end of season 3, and I really think this is the one where it becomes amazing. The Wire always impresses me with how well-written it is, as it's complex from so many different angles, yet it all comes together so seamlessly, but this season is just nuts. The fall of Avon's legacy, his relationship with String upon his return, the development of String as a character, the shit Coleman has been doing to keep the crime rates low, the whole subplot with Carcetti, Kima and McNulty's relationship, etc. All of it just fascinates me, and from what I've been told, season 4 is even better.