Although it’s been available with a workaround for quite some time, iOS 4.0 just went public earlier this week.  There have been reports of device slow downs for 3G owners but 3GS users seem to be having better luck, especially as the number of features lost caused by hardware remains fewer.  You’ve probably been playing around with it for a couple days, so which feature could you not live without?

Multitasking

After three years of waiting in the dark, Apple has finally granted applications the ability to work in the background.  While it’s not full on multitasking, the iPhone 3GS/4 can continue to allow parts of application to work once you’ve changed apps.  Pandora can now stream in the background, apps can finish an uploading task, and you can use VOIP after you’ve switched apps.  It works and I bet a lot of you love it.

Folders

Until 4.0, users were limited to 148 app icons scattered across 9 pages.  While you could technically sync more, they’d only be usable through Spotlight searching.  Folders are a welcome addition to 4.0, allowing you to store 12 applications on an single expandable icon.  Hopefully folders mean less swiping through numerous pages to find that one app.  Spotlight search is overrated and it’s easy to forget it’s there.

ios4features

Unified Inbox

The built-in email app pre-4.0 was beyond annoying for anyone with more than one email inbox.  Having to navigate back and forth between inboxes was unnecessary and tap-consuming.  With the email app overhaul, we’ve now got a glorious unified inbox and threaded messaging to make conversation tracking a whole lot easier.  You might still be missing a ‘Mark Selected as Read’ option but everything else will keep you distracted with happiness, at least for a while.

Fast App Switching

The fast app switcher that allows you to flip from one recently opened app to another works exactly like it should.  While we’re stuck waiting for developers to update their apps to take advantage of fast app switching, once you’ve got your core apps up to snuff it makes a world of a difference.  Everything seems to take significantly less time to do.  This one takes my pick for best feature of iOS 4.0.

Which feature in iOS 4.0 makes you weak at the knees?  Is it one of the big four above or some of the smaller things?  Let us know what you think below.