In my view, yeah. I've played each class in PvP and I find Titan's to be the weakest. Although, if you're getting rekt, I don't think it's the class that's the problem. Each class is good enough to hold their own, but I think the Hunter and Warlock have better skills available for PvP than Titan's. Hunter's and Warlock's have the better supers. Hunter has Golden Gun, which can be shot from 10 miles away and Arc Blade, which gives you additional shields and agility. Warlock has Nova, which can be launched from further away. You don't have to run right up to the enemy and put yourself at a greater risk. Fist of Havoc is good panic super, but to use it effectively, you sometimes have to run a long way towards the enemy, It gives them a chance to kill you before you make it up to them. Ward of Dawn is useful when capping a flag, but can easily be destroyed by another super. Destiny is also massively different to Halo and Battlefield. You might need some more time to adapt to it.