There is absolutely nothing wrong with Adrian Monk, i'd rather watch him or, indeed, any of the old detective/murder mystery programmes over some of the c**p we get on tv these days.
I think the idea of having an obsesive compulsive as a detective (actually he only helps the police as he's no longer a serving police officer) is a great twist. His obsessive behaivoir is the key to his crime solving ability. Although every time I watch it I see Tommy Lee Jones blowing his head off in Men In Black!