From what I can see, you have everything...
-insane mobility
-great AoE
-great single target
-good defensives (blur, darkness, talentable netherwalk)
-good raid utility (darkness, chaos brand)
-fantastic utility (consume magic, 10 yd interrupt that grants resources, baseline aoe stun)
-good burst (meta, nemesis if talented)
didn't blizzard want classes to have strengths and weaknesses? what does havoc not excel at? i wanna know