I think there is much more to Cities in Motion than this. Not only metro but also bus, trolley, tram and ferries. You've got a budget to manage and it's actually one of the very few management games I played in which it's strategically sound to take loans. There are multiple passenger types with different centers of interests and you also have a company reputation with each group.
It's also 3D and quite nice to look at (especially watching your transportation empire buzzing like an ant colony), even though badly optimized.
The only thing I don't really like about Cities in Motion is that it's not very hard at all once you learn a few tricks.
EDIT : also there is multiplayer but I never tried it.
