It's fun for the first 10/15 hours... and then it gets REALLY repetitive. I've played the game since early closed beta.
They need to add more content because missions are "Go to Point A, Go to Point B." Dependent on your threat level, you may have other Players assigned to attack you and you get a max amount of lives to complete your mission.
Where it gets really fun is if you are ever at Max Threat. Then, it's open season and you can attack anyone. However, to get there, you have to complete 6 to 10 missions without dying once.
There are overpowered weapons, but they might have been balanced out in live. Assault rifles with the range of sniper rifles, shotguns with too long range. You pretty much will see two primary weapons on ALL people since they are so overpowered.
Customization is fun though. If you want to customize anything (Music, Clothing, Car, etc.), it's free. You need to have Realtime World Points to sell anything you've customized on the Auction House.
Shooting isn't body location based. So, if you hit someone in the body versus the head, it still gives the same amount of damage.
Beta was plagued by major memory leaks... but hey, it was beta.
It's entertaining... but not really sticky enough for me to buy the game.