Hearthpwn

If you spend money on hearthstone regularly then this adventure is one of the best things to invest your money if you only look gold/money ratio especially when you add golden pack that comes with preorder. But if the cards are bad than it is not worth it. If you start playing wild you should not even consider buying naxramas and black rock because there are few rare/common good cards easily craftable and only one good legendary per adventure.

But in my opinion if you preorder 50 packs or more for expansion then you should definately buy adventure with money too, but if you don't spend money on packs than that ratio money/gold can not be applayed to you and it might not be worth it yet. For example if I could get 50 packs for 5$ I would buy them but for 50$ i won't and I wouldn't buy them even if it was 20$ for 30 packs and than if I go with that logic I will not buy adventure either.

The biggest question is when you have someone like me who occasionally preorder when cards are great and I didn't save enough gold, which comes to about once per year, and then i think it depends on how many more packs of new adventure you want to buy and how much gold you have right now. I have little less than a 1000 and i won't be buying much more packs so i don't need to buy adventure with money