Yesterday we listed the Top 10 reasons to upgrade to Android 4.0. Well, it wouldn't be fair if we didn't follow up with the Top 10 upgrades on the iOS 5 side of the fence, right?

1. SiriThe iPhone's voice recognition isn't perfect but it's the most impressive artificial intelligence we've seen in a commercial product. (Currently only supported on iPhone 4S.)
2. Proximity remindersAn iOS device can remind you to do something when you get to the right spot -- not just at a particular time. So simple but so brilliantly useful!
3. iMessageApple's new instant messenger blends text messaging with IM, and sends SMSs (free) over the internet if the person at the other end has iOS 5.
4. PhotostreamYour last 1,000 or 30 days’ worth of photos are automatically backed up to Apple's servers and synced to all your Mac, PC and iOS devices.
5. Notifications No more obstructive dialogue box-style alerts. Apple took its sweet time designing it, but now has the most flexible alerts system of any mobile OS.
6. Reading listAdd interesting web pages on your mobile to a reading list and read them later on your desktop PC/Mac in the Safari browser (or vice versa).
7. NewsstandYou can now subscribe to publications and have them delivered to your iOS 5 device in the background so the latest issue is always ready to read, without delay.
8. Wi-Fi syncYou'll only need the white iPod cable for charging now -- everything else can be synced with iTunes over Wi-Fi, and the phone can even update its software over the internet.
9. Multi-touch multi-taskingOnly available on iPad 2 for now, iOS 5 lets you switch apps by swiping four fingers across the screen -- no need for complicated app switchers.
10. Camera improvementsDouble-tap the home button to access the camera even when the phone's locked, and snap a shot with one of the volume buttons. Basic photo editing is now included, too.