The Genn/Baku discussion is very interesting to me, because nearly everyone wants to see a nerf, but no one wants to Warsong Commander them. Blizzard can't just change their mana cost and call it a day.
Personally, I find the Death Knights to be the greater design miscalculation. I actually hate Rexxar the most of them all, lol. There's not a single Hunter deck that wouldn't run him (except for Odd Hunter which cannot) - he's a near infinite value machine PLUS a board clear in a class, thematically and historically, that has never really had either of those tools in their arsenal. It's not fun to play a deck that can both 'hunt you down' and outlast you in the long game. And it's crappy design to have a card that is auto-include regardless of your decks archetype or game-plan. Some of the other DKs if played on curve, or before you can play your own, feel like instant win conditions: mainly Jaina and Guldan (in addition to Rexxar).
But of course, I've played all those Death Knights, and enjoyed it because they're powerful cards. Build-a-beast is a really fun concept. The DKs will continue to find a good home in Wild.