Another thread got me thinking but after the changes to demo and state of things in both pvp and pve it is fair to say the spec could use some updating. Yes its clearly still viable if you have top gear, are Zinn, etc but regardless its still not in a place that you could call good design. User friendly is something demo isn't. Skill cap is one thing...where its gone to presently is subjectively too far if you have to be an extreme top raider w' years of experience to execute it to the level other specs perform at with simply correct play.
We've seen the plethora of nerfs to virtually every aspect of the spec yet it still CAN perform. Problem is a priority list so confusing to even an experienced player they are unlikely to want to use it barring some love of the spec itself overriding their otherwise balanced judgment.
Demo has virtually no presence in pvp. In some of the best possible gear your corruption ticks for under 2K, dooms get dispelled almost 2x over before even ticking, the pet isn't scary to any spec of any class (compared to say a bm or unholy pet?! C'mon), and its nukes are nowhere near worth their cast times even ignoring the overarching pvp reality that long casts don't happen anymore. Fel flame (primary pvp filler) actually does more damage to the warlock in terms of mana cost that must be lifetapped back than it does in damage to our enemy. Chaoswave...once a killer is now a joke. In testing in rated play in pvp gear vs pvp gear (no koto or zerking cheese buffs) the highest crit we were able to hit was about 70K. Without CD stacking that number is very significantly lower. With a sub 2% chance to double crit you can see the figures just don't add up to functional in pvp. Hell if you try to use the dark apotheosis form you get a full fledged tank debuff yet that form repeatedly gets nerfs so it clearly is NOT a tanking option. You can't tank but you pay the tax for it in other words while not even being that "tanky". Offensively the spec lacks the burst to kill anything while also lacking any kind of spread pressure to rot a team.
All this brings us to the real topic..."where should demo go from here"?
PVE I think demo needs to streamline a bit. Corruption has become awkward and contributes very little damage. I would much rather move its damage and DF generation into shadowflame/HoG through extending the duration. Fel flame needs to be treated like arc blast...a short duration stacking cost. Say 25/50/75/100% of live on a 4'ish sec timer? It should be useable cheaply but conservatively but expensive to spam. As for void ray its always been very awkward...I'd prefer a shadowbolt volley (lore) or a dark chain lightning. In that capacity it somewhat fights immo aura for a role...unless one were melee'ish and one truly ranged. ToC needs to scale better with haste...or give it a role of say extending shadowflame stacks per use and granting MC charges akin to ember bit generation. That would give a sustained DF use model and a max burst DF model.
PVP demo needs quite a bit of help. Doom needs to refund its DF cost PLUS generate an imp when dispelled. Not quite the UA kickback but it makes tactical dispelling fine but habitual dispelling costly...or at the very least doesn't make the spell a complete and total neutered waste in pvp. If FF were given the stacking cost arc blast treatment it would be a start. Honestly the spell could probably stand to do more damage to player targets the same way CB does 25% less. The lock also should get DF from damage taken ONLY from other player sources...OR just have DF generating spells grant more DF vs player targets. Chaoswave needs to have its 30% nerf reverted. It also probably needs to have the always/never crits but damage scales with crit treatment. Previously the issue wasn't an all CD's CW combo...it was the sub 2% chance to double crit combined with MF making it hit a large area. That's no longer possible and based on what other classes/specs do CW has room to grow. This would normalize that type of damage swings of 2x CW having 4x possible outcomes giving an incredibly random swing variance.
Other minor misc changes might be the siphon life working on shadowflame ticks the same way it works on corr/immo ticks now....pretty easy conversion. Maybe a glyph to use hellfire/immo aura on either a ranged location or even around a friendly target so the lock doesn't have to be in melee to aoe? As for the imp swarm glyph make it a 1.5 min CD @ 4x imps as a baseline ability. Let the glyph take it to 5x at 2.5 mins.
Looking for other ideas/input...maybe steer the spec back to less of a Rube Goldberg DPS machine?