Don't know how many people have tried it out. But it's a decent game. My major annoyance about it though, is the fact that the people that created it. Have NEVER shot a gun in real life or something. Appearantly a 1/16th of Nomex(for those not sure what that is. Its a rubber like material to prevent fire, acid, and contaminents like gas from touching the skin) material can stop a 7.62mm from penetrating the skull... As far as I know... upon impact the round should instantly liquid you're brain. And the fact that you have to wait for the crosshairs to constrict even when standing still. Which is a tedious process when you need accuracy... Other than some annoyances of the MP play, it's still quite enjoyable. The SP is awesome though. Anyone who liked SWAT3 will love SWAT4 in that respect. I'd say its a 3.5-4 out of 5. But it still needs some fine tuning.
-Mithos