Hungering cold doesn't always feel rewarding to use in the situations you'd want to use it. I think part of the problem stems from the fact that it not only doesn't provide a DPS increase at all, but actually hurts your dps by consuming RP that could have been used on frost strikes instead.
A pvper can sometimes look past the above issue due to the fact that it's essentially our only real CC option. At the very least, it can force a trinket or two. Sadly, I think that is the role that it will be dwindled down to in PvP.
But Jayde! You can potentially hit 5 targets with it at once in a 5v5! Yeah, and if you manage to hit all five of your opponents with it, since it's a PBAOE, you're probably fighting people that are extremely bad and have no real sense of positioning.
As a matter of fact, as arena fights become more and more scripted, it will become very apparent that you're fighting a frost death knight (chains applying frost fever is a dead giveaway), and all it takes is a little coordination for your healer to stay away from the DK or DPSer so as to not eat a HC. Going with this, as these fights get more scripted in the arena, it will become painfully obvious when a death knight is going to want to use hungering cold, much in the same way that you know that you'll eat a blind as soon as you trinket X move, or you'll eat a hasty follow-up fear or deathcoil into a fear as soon as the first fear is trinketed. The problem with this scenario? The death knight has to run, or crawl, over to the target they want to CC, which is more than likely NOT going to be the target that they have been DPSing, who's going to typically have more then just disease debuffs on them in any group environment.
Hungering cold as a pvp-only ability certainly has it's flaws, as you can see. I haven't even mentioned just how expensive it is to use as a "snap" ability, because at this point it doesn't really matter.
Here are the issues with hungering cold:
1) It's only usable on trash in PVE. Great, but other people in the group are going to be doing CC already, as is. Besides, if you need HC to clear an instance, then the instance probably needs to be retuned. Not to mention, if you need HC to do every pull, then the one minute cooldown becomes a thorn in everyone's side. An ability that really only helps on trash is far from exciting, at least for me, for a 51 pointer.
2) It's very, very situational in pvp, and will have counters as people learn how to effectively CC/control DKs from getting it off at key moments. Yes, you might be surprising people in the arena right now with it, since they probably A) don't expect it, or B) Don't know what they're fighting against. I promise you, this won't last. It isn't really that difficult to avoid if you're a smart player.
3) It's a very large drain on resources, without actually providing a boost in damage. This is because it provides an element of CC. However, given the two points stated above, this isn't a very good trade off at the moment.
Now here comes the inevitable part where I toss some ham-handed suggestion(s) out. Get ready to cringe!
I have a few thoughts towards this talent, some of which I've held since the beginning of alpha.
1) I've always wanted it to provide an additional debuff of some sort, that is unique to the talent, and not simple be an additional way to spread frost fever. That's pestilences job. I don't want a 51 pointer that basically does the same thing. Pestilence should have always spread FF to unlimited targets, and now that it does, this point needs to be reevaluated. There are many ideas to go with this, such as :
B) Provide an additional "slow" effect for people that are thawing out from the freeze portion of the spell, even after the freeze wears off, similar to an AOE chains of ice
C) The lazy way: Increase the amount of damage affected targets take for X seconds by Y%. Let this debuff work even on bosses, so that it would give us an excuse to be usable on bosses, or on targets that we are DPSing in pvp if we optimal CC positioning simply isn't an option.
2) The only other thing that I've tossed around in my mind about HC, was that perhaps it's just not fit for a 51 point talent, but for a 31 point instead. Going with this, people would be more psyched about going 51 + frost if their 51 pointer was a nice damage ability. My suggestion would probably be to potentially swap howling blast (and increasing it's damage to make it feel more like a 51 pointer), and making HC the 31 pointer.
Why? How many people actually only go 31 deep in frost for howling blast, and then go down another tree? I'd argue slim-to-none. That's because to make Howling blast good, you really have to press on deep further down the tree to make it arguably worth using. Going 31 deep to HB doesn't really do much, at least not the same way you can go down 31 into arms and get MS. MS starts hitting hard for warriors at 31 points in. Howling blast doesn't start hitting "hard" until you're down to around GoG, Tundra stalker levels. This is beside the fact that you need blood of the north to get the most out of it in rotations.
Even then, howling blast takes arguably more "prep work" than any other talent we have. You've gotta get frost fever up, spread it around via pestilence, and then do it as a 1F1U ability. It's the added requirement of pestilence that really makes howling blast feel awkward. It's damage is very lackluster compared to oblit on single targets every single time. It actually feels like our most expensive ability to use. It requires, at the very minimum, 4 runes to use optimally, and I say optimally because any time you are on a single target, you simply won't even think about using HB. Frost fever not up first? Don't even think about using howling blast. In an AOE? Yeah, you can get by with not using pestilence, but why would you? The damage difference is so significant on the off targets if they don't have frost fever up first, that you absolutely feel compelled to use pestilence first.
I guess what I'm trying to say is, if I had it my way, I'd like to see:
1) Howling blast and Hungering cold swap places
2) Howling blast have the FF dependency completely dropped, and do frost-fever type damage all the time. Even with frost fever up, it's still less damage than oblit on single targets. I suppose I'm ok with that, but if it becomes a 51 pointer, I'd actually rather see HB become the better choice between the two for single target damage.
Why? Because oblit has nice crit chance via rime and subversion. It's a "spikier" move to use. Howling Blast is also riskier to use in situations where breaking CC isn't the best option. You have to make a choice, based on player skill, as to when howling blast would be best used over obliterate, even if HB did more damage.
Also, sorry I haven't been posting much lately. Been extremely busy. :)
Edit: Typos and such. It's late. :(