A couple of years ago I would have baulked at the thought of going on a cruise. However, my parents are serious cruise addicts and have gone on several so far. They have been so impressed with them for enjoyment, entertainment and value for money that we ourselves have decided to go during the Easter break.
My parents say that the type of people that go on cruises really does depend on the the cruise line you choose, and this can make all the difference, so check this carefully. There are people of all ages, and families too. The best thing is that my parents have managed to find some fantastic bargains - especially if you can go during school term times where it would work out to be approx £50 pn - not bad considering it includes flights, accomodation, entertainment and all your food. And this price is not just restricted to the med - but also has included places like the carribbean and New York. Also for not much more money, it is worth asking if you can stay at the beginning or end of the cruise as the companies usually have special deals with the 4 star hotels. Eg My parents stopped over in Miami at a central 4 * hotel for a mere £90 each for 3 nights !
My parents love the cruise lines Princess and Royal Carribean which are fantastic for food, and childcare. Thompson was also rated highly especially for their entertainment. Thompson also do free kids clubs too. They were disappointed with the QE2 and Queen Mary. They thought P&O were good too, but didn't think much of Easy and Oceana.
One thing I would check when booking cruises though is accomodating children. This can be very difficult as often the only suitable cabins are 2 bunk beds for the family !! Some don't allow travel cots unless you book the highly expensive suites. Some cruise lines don't actually even encourage children.
Other downsides are times spent at each different ports. These can be as little as half a day so do check the itinery. Also my parents advise checking the seas at the time of year you want to go, as some seas can be quite choppy and potentially ruin your holiday.
Hope you have a fab time