But, hey, I'm more of a fan of Raymond Chandler's Philip Marlowe novels rather than the early screen adaptations, and the movie in my head while reading those books wasn't b&w, either. And neither were Chinatown, or the great 1980s HBO adaptation of Philip Marlowe.
I'd have one note, the best adaptations (and stylistic homages, like Chinatown or The Big Lebowski) replicate the first-person narration not by voice-over, but by telling the whole story from the protagonist's POV (not in the camera-sense, obviously), and therefore having them in every scene. That allows the audience to experience every new bit of information with the protagonist/detective themselves. This series, obviously, went a different route, and it's certainly easier with a runtime of 6-7 hours, to have scenes with other characters.
For example, the cliffhanger of episode 5 gave the audience the information about Cat betraying Ben, but Ben didn't know about it yet. in the proper Chandler-style, the audience wouldn't have been present for that scene, and thus would have experienced Ogden's appearance as a surprise, and would only have learned of Cat betraying Ben when Faber revealed it to him in the lab. There wouldn't have been the cliffhanger for episode 5, but we would have experienced the emotional gut punch with Ben in episode 6.
But otherwise, this show was really good, Cage got to go full Cage in a couple of scenes (especially in episode 6), and the rest of the cast was great, too.