iPhone 4: A Computer in Miniature

The iPhone 4 uses Apple's A4 CPU, the same processor powering the Apple iPad. And it runs the newly renamed iOS 4 operating system (which the iPad will also use, starting in the fall).

As part of iOS 4, the iPhone 4 gains a bevy of capabilities. One of them--multitasking--feels long overdue, but as with Apple's long-awaited cut-and-paste feature, the company delivers on the promise of making multitasking work smoothly.

Quickly double-tap on the home button to pull up a pane that shows which apps are open. From there, you can swipe horizontally through the apps that the iPhone 4 has retained in either a running or suspended state.

When you find the app you want, you just click on the icon. The app will then resume its activity, and, if written to take advantage of this new feature, it will pick up precisely where you left off. At the very least, reaccessing the app will be faster.

Comparative Use Tests

Let's take the example of the side-by-side tests I did with an iPhone 3GS (running iPhone OS 3.1) and the iPhone 4. I navigated between the Safari Web browser and the Photos application and back again to Safari, and then back again to Photos.

iPhone 4: On the iPhone 4 using iOS 4, the phone jumped quickly and smoothly between the apps, with virtually no pause or hesitation. I left a fully drawn Web page in Safari to go to Photos, navigated to a folder within Photos, and then to a picture in the middle of that folder. When I popped back to Safari, I resumed at the fully drawn Web page, and when I jumped back to Photos, I was looking at the same photo I'd left moments earlier.

iPhone 3GS: That same exercise on the iPhone 3GS required the Web page to draw the first time. To change apps, I had to press the home button to exit Safari. I then went into the Photos app and found my image in its album. To go back to Safari, I pushed the home button to return to the home screen and then clicked on Safari. (On one pass, the page loaded immediately; on another, it did not). I then pressed the home button to return to the home screen, selected Photos again--and found myself back at the top-level list of Photo Albums, as opposed to drilling down to a specific image within a specific folder.

To close an app out of the multitasking bar, you click on the icon and hold. The icons then get a red button with a dash; touch there, and you can close the app.

Equally as elegant as multitasking is Apple's implementation of Folders, an increasingly necessary addition. To add icons into a folder, you simply drag one icon on top of the other to create the folder; the folder automatically gets the name of the category those apps share. Or, if you prefer, you can rename the folder on the spot. You can pack a maximum of 12 apps within a single folder (that gives you three rows of four apps across the home screen). And, thanks to the addition of Folders, you can now add up to a maximum of 2160 apps.

Dramatic Camera Boost

The iPhone 4 brings much-desired camera and video recording advances, as well. The primary camera on the back bumps up from 3 megapixels to 5 megapixels, while retaining the same pixel size (which can further improve image quality). The camera also gains an LED flash, a backlit sensor, and an integrated 5X zoom. The camera now lets you shoot in high-def, at 720p, 30 frames per second; in addition, video gains the tap-to-focus feature already available on the camera.

I did not test these features--the lighting at the demo room was a bit funky, and I would have only been able to view the results on the demo device. However, the examples that Apple showcased during its keynote were compelling evidence that these upgrades are indeed worthy ones. These will be among the first features I'll try when I get my hands on a device for our full review.

I didn't fully test the front-facing camera, another addition to the iPhone 4, either. This camera is integral to Apple's FaceTime videophone app, which works only for communicating between two iPhone 4 handsets.

iPhone: Upgrade?

From my early look at the iPhone 4, this handset appears to be a must-have for anyone with an original iPhone or iPhone 3G (the former won't get the iOS 4 upgrade at all, while the 3G won't support some features). And people who have an iPhone 3GS will find this a worthy upgrade, too.

Unlike the previous jump, from the iPhone 3G to the 3GS--which focused on slight performance improvements--the iPhone 4 bolsters the hardware's digital imaging capabilities and its display, making it a comprehensive and measurable upgrade over its predecessor.

[Story updated with side-edging material corrected]