Rehab is one of the sniper rifles with highest accuracy. It also has improved damage than Intervention and allows you to kill enemies quicker making it more deadly.
Rehab is not even semi-auto and it has very low rate of fire. But with some attachments like the Auto Trigger, that can be fixed.
It's speciality is Extremely Low Detection, making you hardly spotted by enemies if you fire from this and that's why Rehab is a deadly sniper.
Rehab is extremely deadly when combined with invisibility.
In Watch Your Back mission all enemies are snipers and wield Rehabs. They are tough to battle but in that mission you are invisible and without it you would have no chances for victory.
Justin wields Rehab for primary weapon and is extremely deadly with it when he activates Wall Hack. He is able to kill you from one shot no matter in which cover you hide. Along with the Rehab, he uses golden Jericho secondary gun.