Yes we went a few years ago when DS was 3. It's basically a huge complex, think more like a suburb rather than a holiday village with lots of appartments and villas plus one hotel.
There are a number of restaurants, childrens club,two spas and a central complex with tennis courts, football academies and so forth.
You pay for everything over and above your accomodation, and its not cheap. We paid over 100 euros for most meals (2 adults one small child), kids club was 60 euros for one day and it cost a lot extra to use the nice pool ( the one attached to our villa in Los Olivos was very cold).
The villas are very well appointed, I don't think I have ever stayed in a nicer one and if your children were old enough to take part in the sporting academies then I would imagine it will be of a good standard - but check its on the week you want to go and how much it cost.
There isn't much else in the area, we ventured out of the complex and found it very high risey and not pleasant at all.
To pay the least I'd recommend booking your flights and accomodation separately - you might be able to get a good deal through owners direct or such like, or alternatively sign up for the La Manga website and they send through some offers.