3 packs is better than one, particularly with a discount on top!
To go with the description on Wizards of the Coasts page:
Draft Boosters are pretty much the same as always: the absolute best way to play Limited. Mythic rares drop a bit more frequently this time around, but aside from that, you’re getting what you’re used to: 10 commons, 3 uncommons, 1 rare or mythic rare, 1 full-art basic land, and 1 token/ad card. Around a third of the time, one of the commons will be replaced by a foil of any rarity. It’s also possible that you get a card in a showcase frame, an exciting alternate version of a normal Zendikar Rising card.