iOS 7 is the biggest change to Apple's mobile OS since Steve Jobs changed his mind and allowed third party apps onto the iPhone.
Where previous iOS updates were largely a case of install-and-get-on-with-it, iOS 7 takes a bit more getting used to.
Don't worry, though: Apple isn't hurling babies out with the bathwater here. The iOS we know and largely love is still there, but it's been given one hell of a makeover.
Let's name the elephant in the room: Windows. In some instances iOS 7 reminds us of Windows Vista, especially in apps such as Maps and Videos where the background shows through the interface chrome, and in others it reminds us of Windows Phone in its use of white space and text.
There's a touch of WebOS in there too, especially in the new multitasking view.
The big question isn't what it looks like, though. It's whether it works well, and we'd answer that with a qualified yes.
While iOS 7 is often a little bright for our tastes - using Safari on an iPad in a dark room after a long day is really quite unpleasant, and a lock screen with four swipeable areas hardly screams simplicity - the majority of the changes are for the better.
The lock screen's new swipes may add complexity, but it's in a good cause. The Control Center, which swipes from the bottom, is an immediate hit: instant access to Airplane Mode, Wi-Fi and Bluetooth toggles, Do Not Disturb, Rotation Lock, brightness, media controls, AirDrop, Airplay, a flashlight, the clock, the calculator and the camera - access that, despite so many options, isn't a cluttered and confusing mess - is a wonderful thing.
Yes, Android's had similar options for ages but you're not going to hear any iOS 7 user demanding Apple drop it because someone else did something similar first. If you find it gets in the way of your favourite apps, you can limit Control Center to the home and lock screens only.
Where upwards swipes bring up Control Center, downwards ones give you the new Notification area. This is divided into three (swipeable) sections: Today, which summarises your calendar and tells you what the weather's doing; All, which records background app updates, push notifications and so on; and Missed, which as you might expect details any alerts you haven't acknowledged.
We're not finished with swiping yet: you can also use backwards swipes to move backwards in apps that support the gesture, so for example you can swipe backwards in Safari or in Settings.
Such swipes take you back to the starting point of the selected app, but they won't boot you out of the app if you swipe backwards one step too far.
With multitasking, double-tapping the Home button brings up the apps list as before, but this time it has WebOS-style thumbnails. You close an app by flicking it away and shouting "begone!", although the shout isn't compulsory.
App Folders are prettier and roomier, and Spotlight has changed too: you no longer swipe from left to right to invoke it; you pull the home screen down instead.
The home screen gets some goodies too. It and the lock screen can use dynamic or static wallpapers, and they can use panoramas too (although that feature didn't work for us). Wallpapers also benefit from a subtle parallax effect, so if you move the phone the wallpapers appear to move.
The rest of iOS 7 emphasises simplicity, so for example the stitched leather is gone from Calendar and Notes don't pretend that they've been written on yellow legal pads. Sometimes it can be a little too stark - Calendar in particular feels like someone's thrown a whole lot of differently-sized Helveticas into a blizzard - but flattening and simplifying iOS does make it feel much more modern, consistent and efficient.