It's a new UI, and a new font called Roboto, for phones and tablets. Many of the pictures you saw were plain wrong. It's polished, it's consistent, it's improved in features and usability.
Most blogs and news focuses on the big changes. But the many small ones, are most important.
The speech input, which is available for over a year now on Android devices, was improved to dictate long texts and make edits afterwards. The camera app now has a panorama function. Take photos and it makes a panorama view automatically. Editing features for photos and videos were integrated. Photo edits has even effects and filters. And a software-enabled fast shot.
You can quit apps by just swipe them away. Same with specific notifications. Swipe them off the list with your finger one by one.
GMail got a big overhaul, too. You can now flip left-right through your mails and having an extended offline functionality.
Google Calendar now lets you "zoom in and out" for seeing more or less information on an appointment.
In the settings, you can not only see the traffic you already used and an prediction when you reach the cap, but you can just set a threshold with your finger. In doing so, Android 4.0 will limit the background data usage. Great for limited plans.
I could go on. Gallery, Dialer, Contacts... it all changed to a even more solid and polished experience.
Check the extensive list of related links to get any piece of information about Android 4.0 Ice Cream Sandwich and the Galaxy Nexus.
By the way: 550.000 Androids activated daily (!) The Androids are marching on. I'll guess they do not care for fallen apples ;)