1. Mac OS is just too unfamiliar. It starts with the keyboard layout, which I reverted to Windows-style after I went crazy trying to find the square brackets. (Which, probably for aesthetics, they didn't bother to print ont he keyboard.)
2. Mac OS's poor multi-monitor support regularly drives me crazy. To their credit, they have ironed out a lot of the bugs in Mavericks, but there is still plenty of stupid behavior (e.g. screen 1 sliding back to the desktop from a fullscreen app when a new window opens on screen 2, or a messagebox from an app on screen 3 opening on screen 1, completely out of my sight). Windows is somehow much better in this regard (at least, I was not annoyed by it that often), and even Linux has very solid multi-monitor support these days (at least for me, YMMV).
3. The userland is UNIX, but does not match my expectations well enough. It's basically in the creepy valley. For example, I was using units(1) one day and wondering why it gave a syntax error when I tried to use a power operator (like "2^64"). Then I noticed that I was in the Mac terminal, not in my Linux VM (where I usually work), and upon inspecting the manpage, I found that they hadn't updated their units(1) since 1991 (wtf).
4. The company where I work is mostly a Windows shop, so corporate IT is based on Microsoft products (AD, Exchange, Lync aka Skype for Business) all the way through. While there are Office for Mac, Outlook for Mac, and Lync for Mac, these are still no match to their Windows counterparts in terms of polish and OS-level integration.
All in all, I'm already set on going back to a Windows notebook when it is time to get a new machine. (It's not like my Linux VM cares which host OS it runs on, anyway.)
I'm not sure it's correct now, but at least it's useful.
The Unix outdatedness is really annoying sometimes. I wouldn't even mind running some kind of big update after getting a new machine and waiting a couple hours for things to improve. The number of Macs I've seen with Linux VMs running on them just to get up-to-date things on them is really unfortunate.
But I don't get the complaint about multiple screens either. It's always been plug in -> desktop extended. I wouldn't even know what to get wrong.
There was always weirdness about the dock and menu bar that's sort of now settling down, but the dock used to display all sorts of bizarreness, especially when it was set to autohide.
Fundamentally it came down to issues with Apple's way of thinking about workspaces, monitors, desktops, applications and windows. Even now I still have to spend far too much time hunting down things across multiple desktops and monitors. It seemed like Apple was dancing around what should probably just happen in an effort not to too closely mimic Microsoft.
But to get at the heart of it, what happens when you full-screen an app? Apple had no idea what that meant when it was launched in 2011. However, what Apple chose to do in the case of full-screening an app on multiple monitors made absolutely no sense and was absolutely useless: the app would take on the role in the hierarchy of a desktop, and the other monitor would go grey. Why? nobody outside of Apple knows, but it took until 2013/2014 to fix.
Everything you need to know can be summed up in the fact that, in OSX, you can click the green button with a '+' in it, and that window can get smaller.
Apple's US keyboards have them in a good place: on dedicated keys to the right of the 'p' key.
Scroll down a bit here:
http://www.apple.com/magic-accessories/
Like you, I am baffled as to why some of their BSD userland programs are so very out of date.
Standard UK layout: https://en.wikipedia.org/wiki/File:KB_United_Kingdom.svg
Apple "UK" layout: http://i.imgur.com/pIGiilv.jpg (@€#@|\`~ are all wrong)
That's an interesting one. OS X has a BSD user land (FreeBSD to be specific), while Linux is traditionally used with the GNU user land. Looking at the FreeBSD site, they ship the same units version from 1993: https://www.freebsd.org/cgi/man.cgi?query=units&sektion=1
I assume you're using a non-US keyboard? I've been using Macs for programming for 15 years, and I haven't seen this, and I have MacBooks Pro from 2010 through 2016 in our office and they all have square brackets on the keyboard.
That is my biggest (and really only) complaint against Apple. Sometimes you have to go under the hood and do a few things. I don't know what Apple has against this way of thinking though.