I'll give it 5 stars just because of how well it looks, sounds and plays. The whole is greater than its sum. But it could have some improvements, including tougher difficulty.
Good:
guns feel powerful, feels epic, Matrix vibe, music, smooth action.
Bad:
upgrading simple offers little choice, too expensive, few things to buy. game is repetitive.
Action part is good, RPG part sucks.
The game is fun when you get the hang of it, but it's too tough. In most jumping games, you can feel exactly where your jump will end up, not in this game. Your jumps are also less likely to be crazy (ie. smaller distance jumps are easier) Also, many of my deaths were simply from hitting a higher ledge and stalling.
I have heard your pleas and cannot deny them; I present to you, Secret Supa-Modesty Mode (Press "M" during play to enter this phenomenal new Mode)!