It's weird how the goal for the new Demonology was to make it the pet spec but it feels like less of a pet spec than the old pre-Legion Demonology. You used to have an array of Wild Imps trailing after you for a goodly amount of time and now you summon a batch for two to three fireball volleys that just vanishes. If you drop Hand of Gul'Dan or Summon Dreadstalkers at the wrong moment in a fight, you waste your damage potential and soul shards because your summon appear, there's nothing to fight and they just vanish, damage potential wasted.
Demonic Empowerment should be a choice, not just a filler button you press after each summon. It should have a modifier list like Blackout Combo and affect the last summon made. Like summon Wild Imps, empower them, dramatically increasing their crit chance and causing them to explode once DE expires, causing massive AoE damage in a specific radius but placing Hand of Gul'Dan on a brief CD. Dreadstalkers explode, their blood appliues a DoT and AoE slow to allow targets in the explosion radius. Add some sort of cost/benefit to DE.
I haven't examined the artifact or look at later talents, so I could be talking out my ass but I sort of get why people are unsatisfied with the spec based off of my playtime leveling a warlock so far.
Edit: Implosion is something that looks like it could be a cost/benefit modifier of Demonic Empowerment.
