The Maldives definitely have a monsoon season, and not much fun if you are there in the middle of it.
Depending on the island that you go to, most are fairly quiet - activities are mostly based around watersports. Great if you are a diver, enjoy windsurfing etc. but can be a bit challenging if you are the sort of person that enjoys lots of sight seeing or hectic night life.
If you are not going 'all in' it's easy to rack up quite big bills. The islands that I have been to all operate on a 'tab' system; you just sign for everything as you have it. If you don't keep on top of it, it can be quite a shock at the end of a two week holiday. We find that by settling the bill at the end of the first week, it was easier to keep track of how our spending was going.
Other than that, it's a beautiful part of the world, and one of my favourite holiday destinations.