DotP 2012 is a huge step up from the previous failure "Duel of the Planeswalkers" (2009) which was a terrible direct port from XBL. While much has been fixed from 2009's release, with improved graphics, UI, and controls, DotP 2012 still struggles to properly emulate the actual Magic: The Gathering card game. The devs are so bent on keeping the players from editing their own decks that they purposefully include simplistic and poorly designed decks. Many decks are binary with boring win conditions and are missing their color's most basic traits, with unlocks only adding bigger numbers and not wider options. However, compared to DotP 2013 and 2014, I think overall this has the best decks. Besides the boring deck design, the real problem with the decks is the unlock system: although you only have to unlock 20 cards total and multiple can be unlocked at once, they lock you out of all the best cards. As you get deeper into the campaign, you are basically forced to continue using one deck, backtrack (or play MP) to "grind" to unlock more, or pay to unlock a deck. This problem is most visible in the Revenge campaign, where your opponents have every card unlocked in every duel.
So what makes DotP 2012 worth picking up? It has the best game modes out of the three numbered releases; Archenemy is great fun because of the wildly powerful effects of the Archenemy's deck, even just with (or against!) AI. With all the expansion decks, 2012 also has the most decks available at 19 total. My favorite are Dark Heavens (B/W angels & tokens) and Ancient Depths (G/U mana ramp & eldrazi). Despite the multiplayer bugs and lag issues, I think this is the best DotP game available and is the best intro to MTG for new players.