I usually stay away from shooters on consoles/non-mouse and keyboard set ups but decided to give this game a go and I don't regret it at all! The aim system is the auto-lock seen on many console shooters and you can fine tune the aim for those head shots with the Mk22.
For a new comer to the series I really enjoyed the story and the “animated” manga style storyboards. Voice acting is top notch. Graphics are great for a PSP but I felt the animations were fairly limited. Only grip is that the color pallate is limited to browns and greens mainly. could be more colorful.
Cool gameplay features include the recruitment aspect where you can assign soldiers to which ever area they are best at, e.g. medic, tech, spy, sneak. I found the NV and thermal goggles to be more of a hinderance than help really, since with thermals on you can't see the edge of a cliff for example, and with a light fog you can normally do without.
Overall, a great game even for those not too sure about shooters on a PSP. Controls take a bit of getting used to, but if you put in the effort you will be rewarded with a great experience.