The problem with it last season was that it didn't scale better than crit in most cases and the BT passive shield effect was way too good for surviving against assassins. The active is also really short range and was bugged for half the season. It works really well on champions who already have % health damage (Vayne and Kindred) or need to auto-attack a lot anyways to do damage (Kalista).
They nerfed it by making it deal less damage AND making it cost more, which means you're paying more for less than it did last season. The passive was way too strong though; it gave you more physical damage (not counting ability scaling or crit) than a Bloodthirster if they had more than 700 current HP. But it greatly delayed building a crit item so unless you could really make use of the on-hit damage and attack speed, an IE + Crit build would outscale it way harder since you would just get three shot before you can get enough auto-attacks off to make up the difference in damage between 250% damage crits.
This season it's even worse since it costs almost as much as an Infinity Edge or Essence Reaver but still doesn't scale nearly as well as crit, especially since it's now much easier to get more than 50% crit chance. It's not going to scale better than an IE/ER build unless the enemy has a ton of HP, but at that point you'd be better of just building a Lord Dominik's Regards and getting the 40% Bonus Armor Pen + 15% extra damage against them than you would be building a BotRK.