OK.......
The advantage of traveling on the ice shipment, once you've survived the initial acceleration, is that it's a straight shot to Mars.
Rather important to check the flight durations though. Drinking water will be supplied free of charge, but you will need to "pack a lunch", or several.
You'll need some air, too. The shortest flight time would necessarily be quite a few months. Even so, it's cheaper than having to build a whole spaceship.