Most of my points have already been made (soldered components, no user upgrades, OS released too early etc.).
However one thing hasn't been said, the direction of OS X (macOS).
At the moment I wonder if Apple has any real plan how to improve if or is everything "throw things at it and see what sticks"?
I don't see much real improvements in the latest OS X versions compared to Mavericks.
Some of the disappointments in the latest OS versions:
UI. Why flatten everything which makes everything hard to see compared to Mavericks. At the moment its hard to recognise if elements are buttons or just decoration. Usability should always be first before looks.
METAL? Nice theory but relatively few developers are using it. Why not support OpenGL or Vulcan which are supported in other vendors?
iCloud Drive. I would trust Apple to manage my files in the cloud and not messing things? No thanks, I'm not a masochist.
SIP. Nice theory but in practice it just creates headache if one uses rarer software.
Mac App Store. I have a hard time imagining anything that could be more broken or buggy. Given the number of restrictions just means most of the software I need can't be sold there so I only open it install OS/ security updates. Apparently its way too hard to code software update that works reliably...
Photos. Who genius had the bright idea handicap it compared to iPhoto and to add insult to injury tie it to OS? While it can be removed via Terminal that is bad design. Separate software would allow benefits such as updates to older OS, user could choose not to install it etc. Same could be said for iWork which is sadly lacking compared to 09 version...
Removal of features in software such as Disk Utility, System Preferences, Console, ColorSync etc. Is Apple serious about keeping its professional users? At the moment I'm very sceptical given the number of features removed or moved to Terminal. It seems macOS is going to be downgraded into a "toy OS" if the current trend continues...
Do not under any circumstances limit the installation of older OS to a Mac that has been updated to newer version. If that happens I will move to another OS because I can't trust company that limits what the customer can do with a computer he/she owns. One of the reasons why I don't use iOS devices is this foolish restriction.
APFS is the only bright spot but I'm very afraid that Apple releases it way too soon and using it without problems would be like winning a lottery...