I checked around Reddit and there don't seem to be any problems with purchasing. I went ahead and bought the bundle for the last 2 wings as I'm out of gold and do not want to grind for them.
This week's release contains good cards for Zoo Warlock in Undertaker and Zombie Chow while Priest and Warrior get good class cards. Wailing Soul might have some niche and cool usage to disable your own negative Deathrattle or frosted minions and Mad Scientist will find a place in Secret-heavy decks. Overall, Deathrattle-themed decks get all their cards from the whole Naxxramas set in this wing.
I've read that this wing will impact the Meta a lot so keep a look out on how these new cards are used in tournaments. For now, I'm looking forward to the new single player adventure additions!