Blood Fear is overpowered - I don't think anyone will argue against that, but warlocks seem pretty weak as a whole in pvp - blood fear was one of the few bits of wreckage that was keeping them afloat. The fact that BF is rightfully being nerfed isn't the biggest issue, it's that no shine is being put elsewhere.
New blood fear either needs multiple charges and / or a reduced health cost, though frankly I'd rather have something that isn't a fear.
At the moment our control is 1 of our Lvl15 talents + fear, we could really use something that isn't another fear at this point, let alone one that only works against melee that are already on you - who are also the ones that seem to have the most ways of getting around fear - and costs enough health that in this bursty metagame that you've done enough damage to yourself that you're probably boned anyway. You can cast it earlier, but then with it's hefty cooldown you fear the first melee attack on you - which isn't much help, you don't start the fight off by deathcoiling / shadowfurying people as your opener.
Personally I'd like to see the health cost either gone or cut to around 5-10% and it be a buff that stays on you and generates 1 charge every xx seconds, some sort of more reliable version of the old dreadmist set bonus.