Mini cruises are perfect for the first time cruiser, and for the person that has never tried cruising and would just like to see what all the fuss is about. On mini-cruises, which will likely not make many if any shore-excursions, you can enjoy the high-life for a brief time and find out if you agree with the massive holiday industry that is cruising. Think of mini cruises as your introduction to the cruise. They are the opening ceremony and initiation.
If you pass through them unscathed you might just find that you enjoyed the experience and then decide to do it some more, on a grander scale, on a future date. On a mini-cruise you can find out exactly which parts of cruising you enjoy if any of them without the massive time commitment and financial pay out that you have to make on a cruise that'll take you to a number of countries, destinations, and ports. If you for example really like the quality of service then you need to make sure that you, when you book a full cruise, go for one that puts a really big emphasis on the service and how it looks after its guests.
While you can learn quite a lot from brochures in this regard you need to also check out things like cruise review sites in order to get a really firm idea of exactly what can be offered. If you like the food on mini cruises then you should similarly choose a cruise line that has an excellent reputation when it comes to the different food that they make available on board. But mini cruises are good on their own too.
Some people just want to be on the boat for three or four days. They might want to have a very short break because that's all that their work commitments allow, or they might take mini cruises because that's the only option that they can afford.
Other might get sick at being at sea for too long, or they feel that there is simply no way that a cruise can be fun for any longer than a week when you start to get bored, and stop enjoying yourself so much. So mini cruises are an excellent option for a very wide number of people who see it is a perfect point in-between not cruising at all, and taking a long cruise that will end up costing them the earth.