Pack 1 looks rubbish.
If Pack 2's Hard Mode is just a Hero mode from previous Zeldas, it should've been part of the main game already. Same might go for the additional map feature, but that depends on what it will do exactly.
Pack 3 has potential to be good. The story and dungeon better be really good to justify the $20.
I really wish these could be purchased individually. I'll definitely wait until all three packs have been released before purchasing and then read opinions on if its worth the price or not.