At face value it seems almost disappointing. After months and months of rumor, innuendo, and speculation about what the iPhone 5 would be, what we got instead was an iPhone 4S. But, between the changes under the hood, and the launch of iOS 5 (rolling out on October 12), the iPhone 4S does come with some compelling reasons to make the switch.
Siri--Your Personal Assistant. Apple has integrated voice recognition into the core of the iPhone 4S. Actually, not just voice recognition, but intelligent, conversational voice recognition. You can just say things like "remind me to call the dentist" or "I'm hungry for a pizza" and Siri automatically knows to set a reminder, or search for local pizza places. It integrates with services like Yelp and WolframAlpha to find the best possible answers to your queries. Many business users already rely on their smartphones, but with Siri an iPhone 4S is like carrying a personal assistant in your pocket.
Dictate Texts and Emails. An extension of Siri and the voice recognition capabilities of the iPhone 4S is that you can also simply dictate text messages and emails. We all know we're not supposed to text (or email) while driving, but now you can create and send messages from the iPhone 4S without taking your eyes off the road or your hands off the wheel. The dictation capabilities let you be more productive during times you are typically idle.
Granted, Apple is just playing catch-up in many respects, and none of these reasons is revolutionary. Android, BlackBerry, and Windows Phone devices are available from all three major wireless carriers--plus T-Mobile, and the various pay as you go services.
Other platforms have voice commands and speech recognition capabilities too. The voice features in Windows Phone 7.5 "Mango" are impressive as well. That said, I don't think any of the rival platforms offer the level of artificial intelligence that Siri brings to the table with iPhone 4S.
In and of themselves, these three reasons don't make the iPhone 4S a game changing device by any stretch of the imagination. But, combined with the updates in iOS 5, the features coming soon with iCloud, and the platform consistency with the popular iPad, these features do elevate the status of the iPhone for business users.