I have the crossbow fully unlocked. Love it.Completed the campaign solo and started World Tier 1 lastnight. The Black Tusk are no joke that's for sure.
It's nice that you can switch between the 3 specials by returning to the white house so you don't feel like you're missing out on something but the crossbow is so bad ass I don't want to ever put it down. Bolts explode after a short delay.
I need to start work on the grenade launcher.