More organised packing system – soft suitcase usually has a more organised packing system with additional pockets and external pockets for fast & easy access while in transit. It is easier and more convenient to travel with a soft suitcase through airports, train & bus stations and cities/provinces as you can simply put your tickets and bottle of water or even umbrella in the external pocket. The soft suitcase is more likely to save the storing space, it's unlike the hard suitcase which is stiff. Besides, it often has an expander compartment that allows 2 inch higher packing space, that means you can pack more things. A soft suitcase is more durable being under checked in the airline, some airline crew treat the suitcase brutally.
last but not least, often soft suitcase is easier to be packed into car boots depending on the shape and how heavy it is.
Unlike the hard suitcase, the lighter a soft suitcase is the more delicate it might be as it is likely made from less heavy duty fabrics or it will have weak features.
Less security, the thieves will be able to cut through the zippers(this can be sorted out with a double zip soft suitcase) or fabric to break into the suitcase, what's more, the others can put some items like drugs into the external pockets without your knowledge
Less protection for the items inside, a hard suitcase will absorb the impact from bumps and knocks, a soft suitcase can't do that more.
Fabric is easy to get dirty, and difficut to clean, comparing to a hard suitcase, hard suitcase can be simply clean with a wet cloth.