Yes, September 13, 2016 has come and gone.
No one seemed to mention that Apple TV generation 4 was getting an update on the 13th but it was there just the same. It would seem to have been about 500 MB, although I didn't check too closely.
I'm usually leery of updating too quickly but tvOS is so unstable that I want every update at this point. It's a lot like the early days of Mac OS X where I was eager to be able to print for the first time, copy reliably to a CD-R, or some such basic functionality. Way back then, I had to switch back to MacOS 9 a lot. With tvOS, you just have to live with what is there.
The update itself went smoothly. The only real change I've used is the dark theme. There was an informational display prior to being able to use the update and the only other one I remember at this point was searching with Siri. I tried using Siri initially but it didn't really help. I still don't have it enabled on my phone, either.
Performance has been improved somewhat. The Galaxy on Fire: Manticore Rising game is a great indicator of how well the Apple TV and tvOS are working, as were the older games in the series. I haven't seen as much of a slowdown when things get busy. I believe I saw only one Network Connection Lost error while I was playing.
Within a month or so, Apple should make another update available to fix some bugs and improve performance further but it's going to be a rather long time until they get a production quality product. Sadly, it may take until the 6th generation Apple TV product before it's truly Apple-like.
If people look at my history, they'd see that I'm generally slow to update iOS because of so many early adopter problems. With almost every major release of iOS or Mac OS X, there have been problems connecting to WiFi. This wasn't really a problem for me with Mac OS X because in the early days, I was connected by Ethernet cable. Of course, trying to use a networking cable is quite impossible at this point for an iOS device.
Thankfully for many people, iOS 10 was not easily available. Some people have had trouble with getting the update from the servers and Apple has already updated (10.0.1) the update, due to (bricking) problems. I remain skeptical and slow to update. When version 10.1 is made available, I'll be more willing to update my phone.
While there are some enhancements, I didn't see anything compelling for me. What would compel me to update would be some huge security flaw in 9.3.5 and it seems as though things are stable with security problems being fixed in 9.3.4 and 9.3.5.
Update 2016.09.20: macOS Sierra (10.12) has been made available, so it seems that everything is finished, except for the bug fixing.
If Siri access is the main reason for the new version, I'm not sure I would bother. I don't use Siri or the phone, and when I tried it on Apple TV, it was less than helpful. I used to use the PlainTalk interface way back in MacOS 8.5 around 1998, which was especially helpful when I was getting ready in the morning.
According to reports, iOS 10 is being implemented much more quickly than iOS 9 was. I saw some article title which seemed to be complaining that iMessage has become the MSN Messenger of iOS. Having used MSN Messenger, I hate to think about that. However, it doesn't surprise me. After years of working to make things simple, Apple seems bent on making things convoluted.
Update 2016.09.26: Encrypted iTunes backups created on a Mac or PC are protected by a password that can potentially be brute forced by password cracking software. The backup method in iOS 10 "skips certain security checks," allowing Elcomsoft to try backup passwords "approximately 2500 times faster" compared to iOS 9 and earlier operating systems.
iOS 10 is up to 10.0.2 already, with several bug fixes. I suspect that there are plenty of more minor bugs and the fixes are being collected for version 10.1 instead of being sent in incremental releases. I'm not ready to take chances.
I got a quick look at it on an iPhone 7 display at Target last night and didn't notice enough of a difference to form an opinion.
The iPhone 7 click-less Home button was interesting but didn't feel like the same technology used in the Mac click-less trackpads that work so well.
Update 2016.10.05: Verizon customers are having trouble keeping LTE active. Apparently, the problem has not been solved with the iOS version 10.1 beta release. Apparently, this is a problem that has been there for some with earlier phones.
I'm still not seeing a reason to change my iOS version.
Update 2016.11.05: About three weeks ago I switched to the iPhone 7, and naturally, iOS 10. It's up to version 10.1.1 now.
It's not exactly finished. Software Update, for example, can't count and has different numbers outside than inside. IMO, humble or not, iOS is almost right when they move to another major version. iOS version 9.3.5 was good but still needed some work, but here I am waiting for them to get to a stable, quick, fully-functional version. iOS 10 should be really good around June.
Having iMessage plug-in apps is interesting, but are they really useful? Automatic birthday celebrations are interesting also. I suppose I worked in software development too long to find these things great.
I was browsing my photos that had been saved to my Mac and found that there were video files for most every photo. This has something to do with Live Photos. Unfortunately, the Camera app defaults to this behavior and until iOS 10.2, you're stuck with it each time you start the app.
I paid for the Camera+ app a few years ago and it's back on my phone now. It's good to be able to handle post processing in the same app I'm using to capture the image. I just have to remember to save to Camera Roll. I also have Snapseed but that works after the fact and is still confusing after quite a long time.
Notifications are driving me up the wall. For a brief moment (iOS 10.1?), the notifications were separated by app and I could clear notifications for a single app and leave others. This doesn't work right now and I either leave or clear them all. I believe there is a way to slide to the left and delete individual notifications, though. I seriously doubt that Apple will ever get these working smoothly--it's only been 9 years, right? It's like the MacOS/Mac OS X/OS X/macOS Finder application. It has traits of the 1984 Mac's Finder but was re-worked in 2000 with the NeXTStep fusion.
tvOS 10 is interesting. I've been able to make folders of apps. It works fairly smoothly. Otherwise, I'm still seeing performance problems. I thought that the A8 processor was capable of handling the iPhone 6 Plus, so why can't it handle the Apple TV box and output a 1920x1080p signal without slowing down?
Apple have a long way to go.