I don't think it's OP it's just too multipurpose. The range coupled with the fire rate and DOT makes it a monster. I get outgunned all the time by TLW at close range but then I just take a few steps back and have the advantage. It has a lot of ways to tackle a problem. I like to compare it to the Mythoclast, back when I started using that my games were getting better mostly because of the gun. With Thorn I'm not seeing much of a difference, even when I'm not using Thorn I don't care if somebody else is because I know it's not always a Herculean effort to kill then, where as the Vex would melt you before you could really get off any bullets. I guess part of the reason I don't mind do much about the Post Mortems is that death is very nearly unavoidable in the Crucible anyway