My son bought this with his pocket money, and he has now had it a couple of days. His reports are very positive, the monkeys are cute and there are all the usual options like feeding, and other caring activities. You get to dress them up in silly outfits. They can have babies, and I think they form family groups too.
I don't know what life span the game has, but it is probably on a par with other sim games - eventually you have run through the options so many times and are fed up with them.
I got it today and have rarely put it down. Good features are that the monkeys look quite realistic for a game and they can mix breed. Bad features are that its hard to control. At first you have 3 monkeys to choose from and can have up too 3 monkeys. when a male and a female monkey grow up and like each other they can have babies. It takes sometime for them to grow up. when you have a baby, things like areas, toys and breeds of monkeys are unlocked.