iPhone 4S looks identical to its older sibling bar the distinguishing birthmark of a brace of top-mounted incisions

The most powerful iPhone Apple has ever made, yet criticized by many as nothing but a cosmetic upgrade. So how different is it and, crucially, is it worth upgrading? We've been living with the iPhone 4S, iCloud and iOS 5 for a few days. 

Out of the box, the iPhone 4S looks identical to its older sibling bar the distinguishing birthmark of a brace of top-mounted incisions signifying that a new antenna design lurks within. Switch on the phone, however, and things are different. Unless you're restoring the data from an older iTunes backup, the 4S doesn't require a computer for activation. 

You can restore the phone from an iCloud account, or set up as a new phone. If you don't have an Apple ID, you have the option to create one. iCloud can also be activated from the phone for storing and wireless pushing photos, apps, contacts, calendars to and from your 4S. The whole process, whether restoring from iTunes or setting up fresh, takes less than five minutes. And because it's the same case design, iPhone 4 users can just swap over their SIM card. Many iPhone 4 owners will be asking themselves why they need an iPhone 4s when the free iOS 5 upgrade will equip their current phone with most of the new 200-odd features.

The new A5 dual-core processor makes things noticeably nippier. Apps launch quicker, web pages load faster, multi-tasking is more fluid and resource-hungry apps like Pages now allow you to edit documents without any lag. Competitors will argue that their phones have been able to produce similar results for months, and they'd be right, but it remains a welcome upgrade. Another benefit of having the A5 processor is to mirror 4S content over Airplay. Wireless, the 4s will push out 720p to an Apple TV. Over connected HDMI, that will jump to 1080p.