Very stylish Michael Mann show that really showed off Chicago in the early 1960's, choosing great locations, classic cars and fantastic music. It was a time when cops could be cops. Although the other members of the MCU were only thinly sketched, former Chicago cop Dennis Farina was great as Torello. The crooks were also given lots of character, from the powerful Manny Wiseboard to the idiot Pauli Taglia. Holman and Ray Luca were also favorites.
In my opinion, the show lost a step when it moved to Las Vegas, but the end of season one where the loyal but stupid Pauli saves Ray only to make their hideout on a nuclear test range was inspired genius.