It depends on the spec.
It's fine for combat because it's filling the hole left by RtBs in the rotation.
It's meh for Sub but this is ameliorated somewhat by premed and the fact that sub has CP's falling out of its pockets
It's really bad for Assasniation because it generates CPs both awkwardly and at the slowest rate so any time you add a higher prio CP spender to your rotation you lose proportionally more envenoms than you actually think you do.
The general issues are; In legion, Assa and Sub were reworked to function without SnD and its blanket return to all the specs jus makes it feel bolted on and not actually weaved into the spec (well that's not true it was never really weaved into Assa even before legion). There's also just the general issue of easily maintained maintence buffs in that if it's easy to maintain you're expected to have it up 100% of the time and if it's up 100% of the time it ceases to be a buff it just means you have to press a button to get to baseline damage.
Hey, mate subs's looking pretty good right now, what covenant did you pick btw?