UI is subjective. I get mildly annoyed whenever I use a Mac. Little things like having to click on a window to give it focus, or having to use command instead of control in many programs, break my flow. I'd probably get used to those if I only used a Mac, but since I use Linux 95% of the time and Mac 5%, I never do.
Honestly, i don't mind the window focusing on mac. What I absolutely fucking hate though, is working on Windows and not being able to scroll on a window that's not active. By default on Mac, if a window's focused, you can scroll another (unfocused) window by scrolling when you mouse is over it. Without having to refocus windows, which is really nice when you're typing something on the focused window.
As for the cmd button replacing the ctrl button. Never going back to ctrl+<key> for shortcuts. The command button is so much nicer to use, it's your thumb vs you pinky. You don't need to stretch you pinky/move you hand slightly to have access to shortcuts and that's so nice. VERY desturbing at first (I hated it), but never going back. Or maybe I've just gotten used to using my thumb. Ultimately, I think it makes a lot more sense though. No more alt-F4 to close windows, its cmd+Q, no more ctrl+B to bold a text, it's cmd+b, cmd+h minimizes/hides your window etc etc.
Also, what i found infinitely annoying at first and that I really like now on Mac, is the window switching with the keyboard. On Windows, alt+tab switches between all windows (including different instances of same program). on Mac, alt+tab switches between applications and alt+` switches between different instances of a said program. I find that more elegant when you have a lot of windows opened, which i always have.
But all these are tiny little things that add up to something really nice to use, but each individually don't and will never justify OS X being the best OS in the world blah blah. You can probably achieve a similar behavior on windows/Linux/whatever. What's nice about it though is that it's the default setup, no third party app needed/config files. You install it and it makes sense. That's why I'm not switching from OS X anytime soon, it's ergonomic, the UI is sick, power user features everywhere, and a real unix. I see it as a linux that works perfectly out of the box. I remember the first month I spent on OS X (coming from 4 years of linux, 2 yr Ubuntu and 2 yr Arch, using both full desktop env (KDE mostly) and lightweigth window managers), everything works and works well and everything is ergonomic and makes sense. Put simply, a Mac never (or very rarely) gets in the way of your work. And that makes a big difference.
But then, I just like Macs because of how I use my computer. I get it that some might prefer a Linux or Windows, and I respect that. I'm just extremely thankful OS X answers exactly what I expect from a computer.
And once you're used to it you'll never want to go back. All of my experiences with focus-follow-mouse on commercial OSes have been almost-but-not-quite right.
> And once you're used to it you'll never want to go back.
Eh. I've used focus-follows-mouse and tend instead to strongly prefer the OS X method of allowing scroll events to percolate to the window under the cursor but retaining keyboard focus on the window it's currently in. This allows me to scroll, say, a web browser on my right-hand monitor, while continuing to type in the left.
Hover-focus is great on tiling window managers, but I'm not sure I'd react well to it where windows overlap by design.
Also, don't forget that OS X lets you scroll whatever window your mouse is over, even if it is "blurred" (not in focus). This is the one feature that I miss most whenever I need to use Windows.
