Bowie's albums up to and including Scary Monsters: Superb, exciting, ground-breaking. Maybe the debut and Pin-Ups aren't as exemplary but they fit in well with everything else, which represents one of the best album runs in rock history. Man Who Sold the World --> Scary Monsters is an unreal line of quality.
Bowie's albums including and following Lets Dance: Mediocre and unnecessary. Sure, some good songs and vibes here and there but nothing special and largely aping either the sounds of the day or his own music from decades earlier.