My initial feedback on the set, before the PTS was out and before testing it, was that the set was probably okay, but only if you want to do a Swallow Soul build. After testing, my feedback was more negative, as the set was too restrictive in how it granted you its bonuses, and (I'm quoting myself here):
"If the set was just a flat Increase the damage and healing of Siphoning abilities by 30%, and decrease their cost by 15%, it still probably wouldn't be worth slotting. It might see some niche use if it had that, but it wouldn't be good just due to how weak that skill line is."
With the new change, let's see what Zos did:
Okay... So the set is now "Increase the damage and decrease the cost of Siphoning abilities by 18%."
So the skill line gives you an okay ultimate, a spammable with a self heal that has the lowest damage tooltip in the game, a healing skill, a single target DOT whose damage is so low that there's no justifiable reason to slot it, a sustain skill, and aoe dps skill that's okay to use. A 18% buff isn't enough to have this set be used, even if you can use the ultimate. Sure, you can spam the ultimate a bit more since you're a NB, but that's basically all the set offers, a 18% damage boost to that skill line's ultimate since it's not like a 18% boost is gonna make the other DPS skills useable. They'd need to seriously buff Swallow Soul to make it useable. It's kind of niche, might see some use, but as it sits, it's like a 5/10. If that. If they lowered the healing of swallow soul to 15 or 20% of the damage done and increased the damage by 20%, then this set might actually be decent, but with how low damage the skill does, it probably needs a 30% damage increase to make this set useable. Buff this set up to 25% or 30% with 15% cost reduction, and buff Swallow Soul up by 20% with that lowered healing, and this set will become a decent pick. Not BiS, but a fun alternative. As it is right now, it just goes right in the trash.
Also this quote from Zos: "As such, we’ve simplified the set immensely while also easing back on its ceiling potential, correcting both some of the insane power the class obtained when not using their Ultimate" Lol insane power my foot.