iPhone apps on iPad both suck and are more awesome than I expected.
Anything text based is pretty poor. Nice that it's an option, but not something you want to use regularly unless you have to. Especially because they use the iPhone soft keyboard rather than the iPad one.
Games, on the other hand, work just fine. I usually forget I'm playing a scaled version once I start. Kind of like TV resolution: 20 minutes into my movie, I've totally forgotten whether I'm watching 720p or 1080p. (Others certainly have different experiences, though!) I've found that several iPhone games (mostly graphical adventures) that I didn't have much patience for on a tiny screen are engaging and fun on an iPad. So for me, the biggest problem with some iPhone games on iPad isn't the resolution, it's the controls: most games with a "traditional" control system (joystick on the left, buttons on the right), would be much better if you could move the controls farther into the corners. Between the iPad screen bezel and the black border that gets added to iPhone apps (they're a slightly different aspect ratio than the iPad screen, so they don't entirely fill the screen), it's hard to reach my thumbs to the controls.
Anything text based is pretty poor. Nice that it's an option, but not something you want to use regularly unless you have to. Especially because they use the iPhone soft keyboard rather than the iPad one.
Games, on the other hand, work just fine. I usually forget I'm playing a scaled version once I start. Kind of like TV resolution: 20 minutes into my movie, I've totally forgotten whether I'm watching 720p or 1080p. (Others certainly have different experiences, though!) I've found that several iPhone games (mostly graphical adventures) that I didn't have much patience for on a tiny screen are engaging and fun on an iPad. So for me, the biggest problem with some iPhone games on iPad isn't the resolution, it's the controls: most games with a "traditional" control system (joystick on the left, buttons on the right), would be much better if you could move the controls farther into the corners. Between the iPad screen bezel and the black border that gets added to iPhone apps (they're a slightly different aspect ratio than the iPad screen, so they don't entirely fill the screen), it's hard to reach my thumbs to the controls.