Not to disagree to much, but its not terrible for pvp. I find that creeping terror is solid addition. I think its very good against LOS healers like operatives to keep pressure on them. I find that DoT's have an added benefit to pvp and that is making the healer work harder. Especially now that almost everyone runs a burst pvp spec its not bad to have a DoT specced player with solid burst on a team. I like it with stealth. I find it helps against teams with skilled players (healers) that are effective. First is they see damage ticking. They may be not healing the right target once your burst players start spiking someone. Meanwhile they have to switch to the guy getting targeted and your 5k dots are still ticking or need to be cleansed.
Against these massive bubble spec teams its always good to try and pop bubbles at range. Madness is good right now if only because it changes your engagement style to open ranged dot, then close to kill. It has 2 long range attacks that hit for internal damage. It gets a fairly good amount of healing going if you dot up the enemy team.
It's weakness is the softness. Your not going to want to go head on against other burst players. You want to harass and flee. Its more of a dps support class. While I agree on its burst lacking the power running it as an assassin can actually produce more wins in pugs than people realize.
Its ok for huttball. Instant Whirlwind and creeping terror are good skills there to go along with improved force speed and more CC breakers per match with advoidance from deception.
One of my favorite tactics. Sitting by the friendly back row. Dot up some people. Watch your melee dps close. Creeping terror the target. Most healers are seeing smash or ravage coming and they are using that aoe cc. One you see that you charge in. Proc up your melee. Slow them. It can really help to kill those healers faster. Meanwhile that off healer is busy working your dot damage and other damage coming at the group.
What doesn't work is a team of all DoT spec players. Mixing in Madness with smash is very nice. IMO.
So, in other words, you run around in a squishy spec trying your damnedest to kite with a spec that has one ability with more than a 10m range, no reduced cooldown on your slow, or no reduced cooldown on your gap closer/maker hoping people don't spot you? I'm all for people playing the spec they enjoy, and am in no way saying that you can't succeed as a Madsin. However, you'd be much better off choosing a 2/31/8 or 0/27/14 spec.
Why fiddle around with DoTs and trying to kite in burst/zerg fests when you can effectively get in, dispatch a soft target in a few globals, exit, CC a support class, and then re-enter to dispatch another soft target while having survivability on par with a Darksin?
Doesn't make much sense to me, but to each their own. I will tell you this. When I spot a sin or shadow in balance/madness charge, I make it a point to single them out for the rest of the match because I know I can burst them faster than they can damage me, control them better and more often than they can control me, and shroud their DoTs---->Medpack and roast them even if they get the jump(which they never do).