In informal speech, how would you describe a bus that travels from point A to point B by passing through every part of the city instead of using the straight way? When you give someone an advice which bus to take, how would you explain that it's not recommended to take bus X because its route is too long?
I would describe the route as roundabout. "That bus takes a roundabout way to get there. It's much more direct to take route X".
I would say circuitous, meandering, serpentine, tortuous, sinuous or labyrinthine. Roundabout is more common, but less fun!
You could say it's a local bus instead of an express bus, meaning that it makes a lot of stops along the way; or you could say that its route is too indirect or too winding, meaning that its path meanders all over the city instead of making a beeline for the destination.
In informal British English, I'd say the indirect bus goes round the houses.
In middle-America the colloquialism "goose chase" is used to describe this. "Goose chase" is also a type of stitching pattern used in quilting because it has the same meandering property.
I like to call it "the scenic route".
Rarely we hear, in New England, "around Robin Hood's barn."
Bus X takes the long way, so I recommend you taking bus Y instead.
Depending on how exactly it traverses the city, it could be called an Eulerian path, although most people would simply call it the "scenic route".