I'm currently leveling a new death knight, with the intent of running as Unholy with my guild once WoD drops. I've always had a soft spot for Unholy; something about combining diseases and decay with undead minions and direct weapon strikes just screams awesome to me.
Unfortunately, there's Festering Strike. Prior to unlocking this ability, I found Unholy akin to a well-oiled machine. I liked the dynamic of strategically spending your Blood and Frost Runes to both maximize your DPS as well as acquire Death Runes. Festering Strike almost completely kills that kind of play style. Sure, you can continue spending your Frosts on Icy Touch and your Bloods an Blood Boil, but there's really not a reason to on bosses, not without gimping yourself.
I think it would be better if Festering Strike replaced Plague Strike, cost a single Frost Rune as opposed to a Frost and a Blood, and didn't increase disease duration*. I also think that Blood Strike should be kept around as a core part of Unholy's arsenal. This means that Frost Runes would be delegated to Festering Strike, while Blood Runes are delegated to Blood Strike (for single target, mind you). Meanwhile, Unholy and Death Runes continue to be delegated to fueling Scourge Strike.
Again, the idea is for Unholy to have a very smooth, rhythmic play style of spending Blood and Frost Runes to gain Death Runes to spend on Scourge Strike. I think it would be a nice contrast to Frost, which is generally burstier and places greater emphasis on anticipating and reacting to procs. Basically, Frost is for blowing things up, whereas Unholy is for dissolving them.
What do you guys think?
* For those who like Festerblight, they can add a Major Glyph that brings that back, e.g. "Festering Strike extends the duration of your diseases by 4 seconds, but now costs a Blood Rune and a Frost Rune."