Needless to say, iCloud binds together all Apple devices and your computer in an invisible, yet important, way. I have found so far that it's awesome. Syncing across devices works as it should and happens within minutes, if not seconds.
I do wonder what the arrival of iCloud will do to data plans. Be very mindful if your data usage is limited, because you could rack up some big charges. While you'd expect the biggest culprits for data leech to be backups and media, document and Photo Stream syncing, that's not necessarily true. Backups and Photo Stream updates require Wi-Fi, and there are options to turn off syncing over cellular for purchases and documents (Settings>Store and Settings>iCloud>Documents&Data, respectively).
If you're worried about using up the free 5GB iCloud allotment Apple provides, you can keep track of how much you've used under Settings>iCloud>Storage&Backup (and you can buy more space if you need to). Remember, though, iTunes purchases and Photo Stream don't count against your iCloud allotment.
There are still a few issues that Apple hasn't addressed. For instance, why is there a volume slider in the multitasking pane, but not one for brightness? I already have physical volume keys; I want faster access to brightness settings.
And I've found that if you're restoring apps on a new device using iCloud, the old saved-states -- the state the app was in when it was backed up -- don't play well with the new upgrade. The result is an app that crashes on launch, but works fine as soon as you launch it again, with no further problems.
Overall, though, iOS 5 brings about a wealth of changes that users from technophobes to technophiles will appreciate and use. Apple isn't first with these features, but it rolls them into the OS in a way that avoids needless complexity. The changes also broaden the reach of iOS in the Apple ecosystem, with iCloud in the background quietly linking everything from home computer to iPad and iPhone.
Given that iOS 5 is a free update and iCloud is a free service for up to 5GB of storage, (not including iTunes purchases or Photo Stream), upgrading to the new operating system makes sense for just about everyone with the appropriate hardware. It's a worthy update that builds on an already strong mobile OS. And it should really perform well on the new iPhone 4S. I'll have more on that after my new phone arrives.
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