I think it was a needed change. Bloodrazor will likely need some buffs, but should be an overall improvement once settled in. The problem that has always existed with Devourer is its stacking mechanic. Becuase it scales well, its provides little in flat stats, which makes champions who buy it very weak early, outside of
of course, who can make up for that with the passive. Plus stacking encourages early passive farming, which means almost no pressure for your lanes. Scaling is as well and good, but on a jungler it's no so great as they are intended to be the early playmakers and make the big differences to the early game. Bloodrazor gives them that early pressure, and still scales decently, since it has %HP damage.
And yeah, the ghost-hit is pretty abusable by some champions, espescially when lower-elo junglers won't be able to punish the scaling as well.