The manual pretty much covers everything (I know, I know, you only rented).
None of the single player levels are staggeringly hard. Some of them (the neutral level where the chibi character throws out all those Attacks First cards and all the elemental levels) have a very specific challenge so they can be impossible or automatic depending on whether you've got counters.
What I wanna know is why you can't browse your opponents' hands. They let you see the hand for a couple seconds when they draw, so it's not like it's a secret, but they don't let you check at your leisure.
Quick recognition of cards based on their pictures shouldn't be one of the skills the game tests.
Otherwise, awesome game.