O2 will not update the Sony Ericsson Xperia Arc, Ray, or Neo to Android 4.0, despite Sony greenlighting updates to its own customers throughout the world. In a blog post, O2 says it has been testing the updates over the past few months, but they didn't meet its requirements. Apparently, the Ice Cream Sandwich update negatively affected the "speed and performance" of all three devices. Because users unhappy with the change would be unable to roll back to Android 2.3 without performing a full wipe of their device, O2 will not be providing the update to any of its customers.
As Engadget points out, any O2 user that wants to update their phone — and doesn't mind the risks involved — will be able to find a fully-functional Android 4.0 ROM online without too much effort. O2's decision won't affect users in other territories, many of whom have been reaping the benefits of Ice Cream Sandwich for some time now.