Our family - two grandparents, three parents and four kids - chartered one of the Wondergulets gulets for a 7-day cruise to all of the small, volcanic islands just off the north coast of Sicily.  In every possible way, it was the best family vacation we've ever taken.  The boat was great with comfortable cabins (smallish, of course), excellent eating area; lots of places to be in the sun; air conditioning at night; and a number of on-board activities for the kids (paddle boards, kayak, etc).  The crew was even better - totally friendly and went out of their way all the time to make sure that we were happy and doing the things we wanted.  Their English was a bit limited, but that didn't really make much of a difference as they could communicate in many other ways.  Our cook was great (more below) and the young deck-hand was incredibly kind and caring to our four young kids.
Our typical day was to have breakfast on board; cruise (sometimes with sails and sometimes just the engine) for a couple of hours to a new destination where we would swim, snorkel, and then eat a fabulous 4-course lunch prepared by the cook.  Following a post-lunch swim, we'd then head for the port where we'd spend the night.  These ports range from mid-sized with lots of stores, restaurants, etc to quite small villages with only one or two restaurants.  But, all were fun to explore.  A couple of the ports had hikes up to the island's volcano crater which added a little exercise and interest to the on-shore activities.  We had chosen to eat breakfast and lunch on board, but to have dinner off the boat, and that's what we would highly recommend to anyone.  The meals on-shore were superb, very reasonably priced and huge fun.  We avoided tying up to docks at the ports where we stayed which was a good decision as it meant we weren't bothered at night by any on-shore noise or activity.
So, what were the bad points?  Not so many.  The boat didn't have wi-fi which we solved by buying a SIM card so that one of our cell phones could serve as a hot spot.  A couple of the kids got stung by jellyfish which caused a few unhappy moments.  The crew said that was unusual, but you should be watchful for them.
All in all, a truly wonderful trip we will remember happily for a long time