This is mostly due to the nature of the gameplay - with each new level you may be expected to perform on foot, in a car, a hovercraft or in control of a heavy machine gun. This removes any chance of the game getting monotonous, though if there's a particular mission type you prefer then you may find yourself getting bored waiting for it to come up again. Pursuit Force really shines during car chase missions, when you can jump from car to car popping baddies in the head and ramming into other vehicles on the road. Not only is it great fun, but it looks pretty good too.
Graphically, the game is great for a PSP title and the cutscenes in particular are stunning. This is aided by the wonderful animations that permeate throughout. Pursuit Force also has some excellent voice actors who help convey the ridiculously over-the-top story of a Fantastic Four style hyper-patriotic police force. Along the way you'll encounter Brits, Russians, Hillbillies etc - all of whom must be dealt with in order to keep America protected.
The game appears to be a decent length and should keep you coming back for more with additional challenges for each level, as well as a separate mode which allows you to play again in order to collect stars. These stars can then be used to unlock various pretty things in the shop.
Pursuit Force: Extreme Justice is already out in Europe, so those of you who are fans of the previous game can go ahead and import it if you like. Otherwise, the game will be available early next year in America.