Improved combat system - Now you can use cover and also a target lock system, which allows you to take out targets with greater ease and accuracy. Plus, you can engage in some hand-to-hand combat if you can't get your hands on a piece quick enough.
Cell phone - Not just for basic phone calls anymore. Use your in-game cell phone to receive missions via SMS, snap photos, and ZiT (tag) songs that can be downloaded exclusively on Amazon.com/mp3.
Free time - In between missions you can take advantage of "me" time. There are gentleman's clubs, comedy clubs, bowling alleys, and bars, which all house unique activities.
Take a break from the storyline - A variety of side missions allow you to help run a car service, "borrow" cop cars, assassinate targets, help solve problems for those on the street, or take to the air with stunt jumps that are scattered all over the city.
Control your own fate - Throughout the game choice moments will arrive causing you to make a decision that will affect relationships and money