Very few death knights play the unholy spec these days. Maybe you don't like the play style, or (ahem) have RP reasons to stick with frost. Or maybe you see the parses and simulation rankings, and just go with what seems to be the highest dps spec. Unfortunately that's a self-perpetuating cycle, as without sufficient data we can't give the unholy spec a fair evaluation. With that in mind, if you play as unholy and are willing to share logs with the community, please reply either in this thread, or in Magdalena's thread on the official forums:

Unholy Death Knights: Post your numbers here - Forums - World of Warcraft

Please include a little bit of information about your gear for the raid of any parse you link. Your weapon and your overall item level should be enough to make comparisons.

Unholy death knights were buffed with patch 5.2, but so were frost death knights. Blizzard doesn't want people who prefer one spec to be forced to play the other -- either direction. We can't tell if this goal was achieved without evidence. Note that our goal at this point isn't to prove anything to the developers, but to the player community.

Due to various factors, unholy was widely neglected in tier 14 content. Partly this was sampling bias with the best players in the world choosing frost and other players following their example. Partly it was features of the frost spec that made it a better choice in key situations. Partly this was due to players not taking full advantage of unholy strengths. And partly it was due to the simulated dps profile not taking advantage of its strengths, placing it unfairly lower on patchwerk rankings.

The simcraft developers are working to address this last issue and increase disease damage to better reflect optimal behavior. In the meantime, in game logs showing frost and unholy death knights side by side will help us evaluate. Thank you to everyone who contributed to earlier log requests. The newest can be found here:

Unholy DKs in 5.2: Show us your numbers - Forums - World of Warcraft

I'll go unholy next week on normal farm since it's the same thing as 2h in terms of reforges etc.