We're going to assume that the difficulty of the series is tuned for iPhone play: Ghosts 'n Goblins games tend to be nightmarish in difficulty even with real d-pads and buttons, and porting that experience directly to the iPhone could only lead to tears. The lifebar from the PSP game will help, but even so we expect Arthur to spend most of the game in his boxers, as usual.
One aspect that is definitely tuned to the iPhone: paid DLC. For 99 cents a pop, you can power up Arthur or Lancelot, get unlimited lives or unlimited access to magic, or even reduce the strength of enemies and eliminate magicians from the game.
If you're feeling brave enough to take on the armies of Satan with just a touchscreen, Capcom is offering the game for $2.99 -- a discount of $2 -- until November 23.
Ghosts 'n Goblins: Gold Knights ($2.99):