Here's a quick link to Gamezebo, who recently named Summoner Wars for iOS their #1 digital board game offering of 2012. They had this to say:
Summoner Wars plays a bit like the unholy offspring of chess and Magic, yet manages to be easier to approach than either of these. Players will select a faction and be given a deck of cards, and they’ll then draw these cards and use them as figures on the board. Each type of combatant has its own unique skill, but since they’re printed on the card, remembering them is as easy as glancing. The object of the game? To destroy your opponents mighty summoner card before they destroy yours.
Not only was the adaptation here flawless, but the game features smart pricing and even smarter multiplayer. Initial access is free, but if you’re enjoying the game (and you will) you can buy additional factions as in-app purchases. And unlike most multiplayer games that suffer from game abandonment issues, players can set a timer at the start of a game to make sure their opponents return. If they don’t, it’s a forfeit and you win.