Fifa and EA Sports have found it hard over the years to significantly improve their games year on year. That's why this time they have put a much greater emphasis on what they call the Player Impact Engine. What this means in layman's terms is that they have completely rethought and redeveloped that way players in the game challenge each other for the ball. How this will effect your gameplay is pretty simple, stronger players like Vidic will be able to push smaller players like Arshavin off the ball with more ease, and when players are evenly matched (e.g. Gerrard and Lampard) the player with more momentum will win possession. The same rules apply when it comes to heading the ball, with the taller players being more likely to win the 50/50 headers. The trailer explains all of this nicely. Sounds pretty simple (dull) on the surface, but we're assured that there are sensitive controls that make this part of the game engaging to gamers.
Fifa have also looked to develop the tactical side of the game further too, especially in terms of defending. Developers have announced an 'all new Tactical Defending' feature. In short this means that you're going to have to use your head a little more when is comes to player positioning and getting your timings right when you attempt to intercept the ball or make a tackle.
Finally, as you would expect from a new Fifa game, they've also updated their skills section so you can take on opponents will the latest tricks and skills.
Whether these additions are going to be worth forking out another £40-£50 for is too hard to say without having a play on the game first. So in the meantime you'll have to make do with the official trailer and watch the space until the full game review is ready.