Death Knight. Death Knight. Death Knight. Death Knight. Death Knight. Death Knight.
Every game is the same. Every game is miserable to play. I either narrowly win from top decks or get completely crushed because this class has everything.
It’s just awful.
The funny thing is that people will come in here and tell you that because 9 of the top 10 decks AREN’T Deathknight then you’re wrong. I have the exact same experience. Most of my games are against DK and I lose most of the time. They’re so OP BS. Unlimited board clear and far too many easy combos to get off. Because I mainly play minion based decks, I only get placed against them to make sure that 50% winrate stays in place.
Design wise, DK has been very successful. Regardless of its power level (which hasn’t been bad), its popularity has been solid through most of its existence.
I think rune system is helping that more than most people realize. Runes let devs give DKs different themes and deck types with less worry of creating crazy combos between them, since some of the cards.
This also means when facing a DK, what works against one DK deck may not work vs another, which could lead to people feeling extra frustrating if matched with DKs over and over, since it’s not as simple as just building one counter deck and call it the day.
It can be satisfying when you happen to counter the DK though.
Semi-related, today I managed to kill a DK with a very satisfying DH/priest tourist combo
With concierge, I could cast those priest self-damage spells for 0. The DK just happens to be handbuff, so I ran my face into his 10 attack taunt (after killing everything else with the priest drink), so it did 10 back at his face, which along with other things was enough for lethal 
Agreed.
Resounding: no. Rune system is the worst part of DK’s design, creating unique limitation for DK with no upside. Triple Rune cards you say? Yes, they have unique limitation too.
There is a reason Rainbow has been most popular deck archetype for DK before the last expansion. Plague DK is pretty bad, Blood has no win condition. So generally there is Rainbow and maybe one of the three runes is usable.
The main problem with the rune system is that it is at odds with the card allocation per class in a set. Death knight needs more cards assigned to it to make up for the rune system which does not happen.
I think a potential fix for this would be for various rune combinations give a bonus or penalty to your deck.
Example: triple frost - freezing a frozen minion destroys it.
triple blood - all sources of lifesteal deal an extra damage.
triple unholy - gain corpses from enemy minions.
You could a wider access of cards to the various death knight decks while ensuring you don’t need to allocate more cards to the set to deal with the rune system.