cybernetics received a complete overhaul. Now, armor is tied to your cyberware rather than clothing. This means you can wear whatever you want without worrying about your overall defense and combat effectiveness. However, you can't install a bunch of cyberware at once. As you progress you'll increase your cyberware limit, and if you install too much you'll be hit with various debuffs. Not only that, but when you install new cyberware, you'll get to see the installation process from V's point of view
Skill trees across the board have also been reworked to introduce new abilities and perks that should spice up combat.
Phantom Liberty also brings with it the long-awaited revamped police and notoriety system. Now, similar to GTA V, if you commit a crime, the police will investigate. If you're nearby, they will engage; if not, they will search the area. As you commit more crimes in quick succession, they will get more aggressive, and if you hit a five-star wanted level, MaxTac, a SWAT-like special forces unit in the Cyberpunk universe, will show up. Sasko told us that bosses will spawn in the world if you get your notoriety high enough
Phantom Liberty introduces vehicular combat and weapon-mounted vehicles. Using the bumper buttons, you can aim your gun out the window and fire, and if you're on a motorcycle you can wield melee weapons. I don't know how practical swinging a katana from the side of a motorcycle actually is, but it sure looks badass.