I've updated my MacBook to macOS Sierra, and it's rather underwhelming and half-hearted IMHO. And yes, dear eagle-eyed reader, Apple capitalizes the Mac in MacBook but not the Mac in macOS - what a confusing naming (lack-of-)convention. Still, macOS is a better name than OS X (can you say OS 10 10.X instead?)
There are a myriad of articles expounding the latest and greatest in Sierra, but my list is only the negatives. Marketing slogans are from Apple's macOS page.
Universal Clipboard "Copy on one device. Paste on another" - I would rather this be manually trigged and not automatic. Of course there is space constraint on iPhones, but on the Mac, I'd prefer a Edit menu option like "Paste from iCloud" rather than have devices over-writing each other's clipboards and leaking sensitive data at unopportune times. You will transmit even passwords if you use copy and paste, over local Wi-Fi, not over the Internet, but still!
And no, this cannot be disabled.
iCloud Drive "Your desktop and Documents folder. Accessible on all your devices" - what about synchronizing some other folder instead of documents and desktop? I'd rather have a specific folder to upload to iCloud, so I can keep private things private!
I'd say this also is against most companies IT policies, better leave this off and stick with business-friendly tools like Dropbox Business, Google Drive for Work, Microsoft OneDrive for Business. I'm not advocating any of them, but notice the "business/work" focus pattern.
Optimized Storage "When you need more space, let your Mac find it for you" - I need the opposite feature, optimized iCloud! Apps are storing files in iCloud, with terrible naming conventions that don't even reflect the app names, such that I have a terrible time cleaning them up. Ever tried it from iOS? So slow!
Slightly better in macOS, but I can't see all the iCloud Drive files in Finder (they are hidden and hard to delete), and Manage under System Preferences > iCloud intermittently shows the correct icon and a different name (onepassword vs 1password). In my case (though not all iCloud's fault), I have two 1password entries and apps called "App", "Note" (notes?) and "SaveDataWithiCloud", none of which match names of Apps I've ever installed in iOS.
Tabs "Get all your docs in a row" - good grief, I've hated floating windows everywhere on Mac forever, and now we finally have tabs. That still doesn't get rid of most windows, it's not automatic, and causes some programs to behave strangely. But worse of all, you'll have the double confusion of managing windows and tabs in windows! Try it with Pages or TextEdit - the New menu or Command + N will always open a new window (not a tab) and use View > Show Tab Bar and press + to create a new tab. I don't think there is a keyboard shortcut for a new tab either...
Why don't we go all the way and have a Dock that pops up the window/tab list when hovered over, a smarter task switcher, and move menus in the app windows where they belong while we are at it? Oh, that'd be too much like Windows!
Siri "Just like you, Siri can do great new things on a Mac" - except for those of us who work in cubicles, or meet in noisy coffee shops, because you can't easily type a query to Siri (workaround: ask Siri any question, and then type over the question and replace it).
Why can't these capabilities be added to Spotlight instead? Offline. Keyboard access. Deep integration. I'd prefer to just type "facetime mike" into Spotlight. But seriously, thank goodness Apple did not replace Spotlight with Siri or attempt to merge them.
Windows now kinda stick to each other placed side-by-side - nice, but not half as useful as Windows' Snap Assist.
No doubt that to many people, the above are great updates, but to me, they are just not well thought out for a desktop OS! In their current state, I would rather not have universal clipboard, iCloud documents folder sync and optimized storage (since for me, iCloud is full while my notebook is not).
I'd also forgo iMessage and shared Notes for example, and continue with alternatives that are more feature-rich, cross-platform, business-focused, self-hosted, and/or open.
And, why haven't other iOS features made it ? E.g. Night Mode (just get f.lux instead), and the Siri voice for text-to-speech (aka VoiceOver)
I'm sure the big changes like Siri and Photos are really great, but they aren't particularly innovative! Siri debuted on iOS in 2011, and Picasa had face recognition since 2008. Admittedly, the face recognition in macOS Sierra and iOS 10 is uncannily accurate!
But mostly, I feel Apple's lack of focus resulting in less well-thought out features, and half-hearted experiments. How about giving us a bundled (read: free), big, bold new app?
Apple: I'd love a Paint program that can use Force Touch!