Personally i was a little worried this game could suffer due to poor control given the lack of a second analog stick. Fortunately, the control scheme is quite easy to master and in my opinion, the best control scheme ever found for a PSP shooter.
The gameplay is very smooth, and the fact that you are able to choose different approaches to the game helps strongly... not everything should be done with stealth, and neither should you always rely on just firefighting...
The story mode is quite appealing, graphics and sound are basically on top of current PSP titles and the mission mode helps to add a good amount of replayability...
In short this is a videogame no PSP owner should let pass by...