first off , regarding blood fear / burning rush / unbound will:
Amongst the three looking at a clear pvp pov mainly aimed at 3v3 arena blood fear will be the least used talent for any warlock within the top .5% of any battlegroup.
I will now state why so that we can stop these futile posts made by low rated baddies; blood fear seems good at first glance, but it isn't practical enough to pick over the other talents for coordinated 3v3 arena, besides the health cost, the actual need of having an instant fear is extremely low, any decent lock high enough on the charts can fake cast pretty well , blood fear is a talent for newbies who do not have the concept of fake casting and simply spam fear often, which is bad.
fear is used to peel or CC at the right time, most of the time if 2 dps are training the warlock casting an instant fear ( which consumes some of your health ) to peel 1 for only half a second ( not taking in consideration dispels ) would result in a disadvantage instead of an advantage, the only time blood fear would be better than normally casting a fear is when no one is even looking at you, and the team you are facing utilizes LOS extremely well, which can never be the case, warlocks can never be left alone to wreck another team.
Now I will explain why the other talents in the tier are better than blood fear:
burning rush, my personal favorite in that tier, mobility is god ( remember that) , it's what we warlocks crave the most, not some instant fear, we need to move , burning rush is amazingly good, granting us 50% for such a low cost that can be maintained so easily in any 3v3, with the right combos ( IE: hand of freedom on you while using burning rush = unstoppable speed) also as affliction using soulburn port to grant immunity to movement impairing adding to that 50% speed is godlike, kiting double melee or moving to a better position faster to set up kills is way more important that some gimmick fear.
Unbound will, the positives of this is clear, but the negatives ( health cost) might be too high to even consider, if a rogue is sitting on me while i'm in kidney, blowing 20% of my hp to break the stun would be meaningless since I would basically be helping the rogue further pressure me, this will have to be seen later on, maybe something can be done about it, like popping a shield then using unbound will or if you have dark bargain , utilizing unbound will during dark bargain to increase the damage taken after the buff is down so we get more damage shared while archimonde's vengeance is up.
overall this should sum it up nicely, though many will disagree with me, I doubt high rated locks are one of them.
I mentioned in the other thread that blood fear isn't necessary for any organized teams, since locks have clearly dominated in the past without instant fears. Unbound Will is also great, esp. for undead with the imp. You're basically un-CCable. Burning Rush is also great but very situational in random BGs. It's nice for griefing and best if you have Dark Bargain picked for the first talent.
I think Blood Fear is just a big improvement for players who tend to 1v1. I for one usually go 1v1 in BGs and Blood Fear is the most viable especially against a rogue or feral that successfully opened on me. Right now, casting a fear 1v1 is not a good option unless you have great latency so you can time your jukes.