Very thorough, and very well written. There is a metric ton of new features and other cool odds and ends in iOS 5, but I think this intro paragraph from Dan sums up what exactly is so hallmark about today’s software updates:

With iOS 5, Apple’s theory of the post-PC era finally moves into practice. No longer are iOS devices second-class citizens, tethered to the sinking anchor of a personal computer. With iOS 5, it’s possible, for the first time, to use your iPhone, iPod touch, or iPad as your one and only device.

Dan Moren’s iOS 5 Review for Macworld

Nice piece by Kyle Baxter:

Most articles about Siri have focused on Siri’s natural language recognition and how revolutionary it is. While it is integral, it is not the important part. It is the means, not the end. Focusing on Siri’s natural language recognition is like focusing on the original iPhone’s multitouch input; while it is what allows the iPhone’s magic, it is not the magic itself.

Siri as the Future of the Web

John Gruber in his review of the iPhone 4S:

In a sense, Siri is like a second interface to iOS. The first interface is the app interface. Launch, tap, drag, slide. The Siri interface is a different world. As stated above, this new interface is in many ways the opposite of the regular one — open-ended and implicit instead of narrowly defined and explicit. I don’t mean to imply that Siri doesn’t fit in or feel right at home — it does. But Siri is indicative of an AI-focused ambition that Apple hasn’t shown since before Steve Jobs returned to the company. Prior to Siri, iOS struck me being designed to make it easy for us to do things. Siri is designed to do things for us.

“A Second Interface to iOS”

Jim Dalrymple’s iPhone 4S review. Regarding Siri:

Siri is not your typical voice recognition technology. You don’t dictate to Siri, you interact and have a conversation with Siri. It’s difficult to explain how good Siri is, but you’ll find out soon enough.

Maybe Siri being iPhone 4S-only truly is just a sales tactic. Maybe Apple is confident that Siri is so great and clever that it will actually compel a decent amount of people to upgrade who weren’t otherwise planning on it. However, on the other hand, for some reason that doesn’t sound very Apple-y to me.

“I Hope You Don’t Say That to Those Other Mobile Phones, Jim”

MG Siegler’s review of the iPhone 4S. Regarding Siri:

A number of folks have written that while Siri looks good, it seems like a feature that gives good demo but won’t actually get used. I disagree. I think this is a feature that will sell the device. And I think all of Apple’s rivals will have to act quickly to counter it. We’ve all seen the science fiction television shows and films where people talk to their computers like human beings and the computer understands them. That future is now.

“This Is the Best iPhone Yet”