It has been hailed as the great leap that will make Jony Ive the successor to Steve Jobs. Others say it just takes too long to download - and that their alarms failing to go off this morning was a seriously bad start. So which side are you on? Do you believe the hype, or is it, after all, a flashier but more irritating version of the software we all knew and loved?
For those iPhone users yet to download the new operating system (get moving, people!) our guide shows the old and the new back to back.
Let us know how you're finding the new system in the comments below.