I never tried it, but I think it may actually be better than point to point routes for two reasons:
1) shortens time to each city (you always get q city distance A-B B-C A-C and not two cities distance A-B-C). This should maximise occupation and, if the cities are connected to other cities, you might even end up transporting passengers farther.
2) trains should never wait for each other at signals or stations (I often use full double tracks to avoid this).
However, there may a few disadvantaged I can think of:
1) you will probably need to lay more track (this can be a problem in the beginning where you have limited amounts of cash, afterwards it is no problem as track costs little comparing to running costs)
2) you may need to use more trains (since tracks are longer and maybe because of the two directions) and therefore higher running costs.
It would be interesting if someone makes an experiment.