It's impressive how it manages to keep so close to the movie, and it's great how the fighting style requires a bit more cooperation that the standard GTA mash-a-button. It's fun walking into businesses, grabbing the store owner by the neck and smashing his head into his own till (or shooting him in the foot, or throwing him through his window etc. etc.), extorting him until he agrees to pay you for protection, and it's even more fun finding out that they run an illegal casino behind the shop that you can also take control of.
You must also take over your rival families' warehouses and hubs, that's where the big money is. The only way to become the Don of New York is to make sure every business pays you, and you control everything that enters and leaves the city.
It gets repetitive, there isn't much variety when it comes to cars, and a lot of the shops/hotels/bars that you can extort also look very similar, but when you understand that there are no loading times while you drive around, and the story is so close to the movie, and that it is actually a challenge to become the Don, it makes it worth playing. Very addictive, and very fun.