Having interfaced with Apple in a different way (apart from owning a new MBP and an iPhone X) I'd say the issue is, and continues to be, growing pains. They're certainly losing the lead in software engineer talent (giving it away to whom, I'm not sure). But the single most horrible experience I've had with Apple in the last year was trying to get software published on the App Store. That's a department that's so larg…
The app store and code signing have been fairly bureaucratic to deal with from day one. It's actually improved compared to the initial years from turn around times measuring in a day or two vs a week or two. I remember doing such tricks such as resubmitting the same binary and it getting passed. It really is a dice roll.
Compile times comes from swift and promoting it too early because it was too immature. If you write your code in objective-c, your fast compile times will come back. Swift compile times have been improving as time goes on.
They also don't pay as well compared to google or facebook. But even then I think it's more a management thing, since they determine the priorities in software dev.