While unorthodox in appearance, operation is straightforward blowback and this lightweight weapon may be wielded with one or two hands. It's bottom ejection feature makes it ideal for left handed shooters.
With a 50 round capacity magazine, the FN P90 has very mild recoil and is extremely controllable when fired in the full auto mode. While the trigger wasn't remarkable, burst fire may be achieved without difficulty.
Its size and weight makes it ideal for both SWAT teams and AFV crews (try climbing out of a hatch with a rifle), it's a wee bit on the large size for discrete executive protection.
Switching to the bullets, it is my understanding that these high velocity bullets are capable of penetrating body armor.
A newly organized SWAT team would do well in adopting this weapon. Administrators who disdain at the menacing appearance of the shotgun or abhor the presence of a menacing carbine in the patrol vehicle may not look so unkindly upon the FN P90. Considering that patrol cars are getting smaller, why not have a smaller firearm?
By the way, fun to shoot.