It is not best PSP game out there. Still it is amazing looking and solid gameplay.
It has great set of weapons, solid controls (choose what you like the most from settings) interesting hacking system and this all covered with great looking in-game graphics. It looks better than many PS2 FPS games and definitely sets bar up high for PSP games. It has fake HDR effects and crisp textures that makes you wish you would see this stuff topped with better story and enemy AI.
It is not complex tunnel-driven modern FPS with cinematic story, it is like your placeholder FPS on the go which gives you good enough of satisfaction and action.
I wish Konami would use this game engine and this team to make something spectacular, cause seriously, this game has something that made me think that "HL2 for PSP" is not that distant dream after all.