iOS 10 went out to everyone today, and my Settings app has had that little red "1" badge on General since about 10am. I'm not installing it the second it's live and honestly neither should you, at least not on your only phone. I did that with iOS 8 back in 2014 and spent an evening watching a progress bar while my phone sat bricked-looking on my desk. Lesson learned. So here's what I'm actually doing before I tap that button, not the generic "back up your phone" advice you've read forty times this week already.
Actually check your backup, don't just trust it
Everyone says back up to iCloud or iTunes before a major update. Fine. But go one step further: open iTunes (or on the phone, Settings > [your name] > iCloud > iCloud Backup) and look at the timestamp. Mine said "3 days ago" which sounds fine until you remember I switched to a new case, deleted a bunch of texts, and took about 30 photos since then. Force a fresh backup, wait for it to actually finish, then update. Takes maybe ten minutes over decent wifi.
Know that "slide to unlock" is gone
This is the one that's going to trip people up the most, and nobody's writing about it because it sounds too small to matter. In iOS 10 you don't slide anymore, you press the Home button to unlock. If you've had muscle memory since 2007 for that little swipe gesture, give yourself a day or two of fumbling. I tested the beta for about three weeks this summer and I still occasionally jab my thumb at empty screen space out of habit.
Check your iPhone model before you get excited about widgets
iOS 10 needs an iPhone 5 or newer, or a 4th-gen iPad or later, or a 6th-gen iPod touch. If you're still rocking a 4S, this update isn't coming to your phone at all, sorry. On supported devices you now get widgets on the lock screen (swipe right) and Notification Center pulled apart into "Today" and "missed stuff" tabs. It's genuinely useful once you set it up, but Apple didn't make it obvious how to add widgets, so go to the bottom of the widget screen and hit Edit.
32-bit apps are on borrowed time
If you've got some ancient app you've been using since the App Store basically started, iOS 10 will pop up a warning that it "may slow down your iPhone" if it's still 32-bit. It'll still run this time around, but that warning is Apple's way of telling you the clock is running out. Worth checking now which of your daily apps throw that warning, so you're not scrambling for a replacement later.
Messages effects are fun for about a day
The new iMessage stuff with the confetti and laser bubble effects and the tapback reactions is cute, I'll give it that. My sister sent me a message that exploded into balloons this afternoon and I laughed. But I give it two weeks before it's the most annoying thing in every group chat I'm in, right up there with everyone discovering GIF keyboards in 2014.
One more thing that's not really about iOS 10 but is eating my Twitter feed today: half the people I follow are dealing with Note 7 exchange logistics after Samsung's recall announcement a week and a half ago. Best Buy near me apparently has a line for it. Rough month to be Samsung's PR team, and a weirdly good month to be the person who just wanted to buy AirPods and instead has to explain to their mom why her phone might catch fire.
Anyway. If your backup is current and none of your critical apps throw the 32-bit warning, go ahead and install today. If you're not in a rush, there's no shame in waiting until this weekend and letting the update sit for a day first, in case anything ugly shows up. I'll probably do mine tonight after work, over wifi, with the phone plugged in and not glued to my hand for twenty minutes. That's really it. Not everything needs a dramatic writeup, some days it's just a checklist.