The Thor vs Superman thing is interesting. You can't have Superman lose, as he is the reason that the Superhero genre even exists, so both DC and Marvel owe everything they have to him. Then again you have Thor, one of the archetypal characters in classical ancient mythology; a source of literature which is commonly held to be the inspiration behind most modern superhero comics. Thor was one of the most popular figures in all of the ancient Greek and Norse tales of superhuman beings, and without their influence on Western society it may have been possible that the concept of modern superhuman heroes, like Superman, may never have been thought of at all. It's almost a 'What came first, the chicken or the egg?' argument.
However, in terms of a fight, that is a magic hammer and should have exploded Superman on sight. Also, for an opponent he describes as the toughest he has ever faced, he appears to take him down in a couple of panels. He seems to have forgotton about Doomsday too I guess. On the whole I enjoyed this issue though.