Planetside 2 uses a brand new engine called ForgeLight built specifically to support next generation games from SOE such as Planetside 2 and Everquest Next, Planetside 2 will be the first game from SOE to use ForgeLight. 
The engine has been designed from the ground up to scale across many different types of hardware, Planeside 2 is expected to run on hardware up to 4-5 years old
The scale of the game will be huge, many seamless, non-instanced continents make up the world of Auraxis with hints at new planets to be added in future during the 3 year post release plan.
Hit boxes will be improved to add head shots which do greater damage, current plans during testing are to award different damage bonuses for different weapons, sniper rifles may have high bonuses such as 200%, some weapons will have no bonus such as a chain gun and vehicle weapons.
Vehicles will also have locational damage.
ForgeLight supports many new graphical enhancements such as: 
- Real time Radiosity
- Advanced Atmospheric Scattering
- Volumetric Fog
- Screen Space Ambient Occlusion
- Advanced environmental lighting
ForgeLight will integrate PhysX by Nvidia and will be used to create more realistic and skill based vehicle handling, as well as simulate bullets correctly including bullet travel time and bullet drop over distance. 
ForgeLight supports day/night cycles. Although it has not been officially announced as part of PlanetSide 2, Matt Higby has confirmed that it's something the team are working on.
Environmental destruction has been hinted at as a possible future addition to the game 
Many game related data will be available externally by an API. This should include character stats, world stats and battle information. There may also be a limited input API.