Invisible Shield for Apple iPhone 4!“iOS 4, previously known as iPhone OS 4, is a major update to Apple’s mobile OS which brings a handful of significant changes—namely Apple’s implementation of ‘multitasking’ plus the opening up of thousands of APIs to third-party developers—while the rest of the improvements are basically tweaks to existing functionality,” Jacqui Cheng reports for Ars Technica.

“For iPhone 4, iPhone 3GS, and iPhone 3G users (as well as second- and third-generation iPod touch users), iOS 4 will add useful functionality that will make your device more useable than ever,” Cheng reports. “For the purposes of this review, though, we used iOS 4 on an iPhone 3GS—the most current iPhone available ahead of the iPhone 4 launch.”

“The most exciting part about iOS 4 is really what third-party developers will do with the 1,500 new APIs. After all, the iPhone experience has become one that is almost defined by its apps, and Apple has opened up a new world of possibilities with its latest API offerings. As we go into the second half of 2010, we’re sure to see plenty of new apps that do creative things with Game Center, multitasking capabilities, the camera, and more,” Cheng reports. “So, unless you have a specific reason to hold back—jailbreakers, we’re looking at you—or you’re a poor, abandoned original iPhone owner, we can’t see why you wouldn’t want to upgrade your iPhone or iPod touch.”

Read the full, comprehensive (as usual) review here.