OCModShop posted a review on Space Ace for the iPhone
There are a few advantages to the iPhone version. For one, you can resume the game if you are interrupted for any reason, such as if a call comes in. If you set the game to "infinite lives" then you'll never have to restart the game ever. Just press the Home button to exit. However, once you're in the middle of a game, there is no way to get to the main menu. Basically you have to restart the application and answer "no" to "would you like to resume your previous game?".Space Ace Review (iPhone) Review