For a number of reasons, I was recently "forced" to work on an Apple machine for longer than I would have liked. Don't get me wrong: I like OS X, and I think there is a great deal the open source community can learn from it. However, it doesn't seem to be geared up for people like me: 11000 emails literally kill Apple Mail, for example; or, spotlight can be fine for a small home-user folder, but try it on my home directory...
What have I learned from my Apple experience? I learned the power of integration. It's clear that there is very, very little "code duplication" in OS X. For example, the text editor you get in pretty much every Apple program (Apple Mail, TextEditor, and pretty much everything else with an editor in it) is clearly always the same one. This could be considered an implementation detail, but I can tell you that users notice it, because everything is so consistent.
The same thing can be said about applications: there is "one" of everything (one addressbook, one program to manage your photos, and so on).
Linux, on the other hand, is all about choice: there are many, many ways to do anything. The divide between KDE and Gnome is a prime example. It is true that the open source ecosystem tends to ensure that the best supported and most used applications tend to emerge. However, in Linux if you want to browse the Internet you can pick between Konqueror, Firefox, and so on. To write your email, you can use Kmail, Thunderbird, Evolution. All of them have their strengths, and ll of them are fantastic.
Apple's advantage doesn't bring only benefits. They can make sure that they reuse their code as much as possible, and that every single piece "fits" in the whole system, but this comes at a price. For example, when they introduced Spotlight to search documents, they realised that email (which was in a standard format) couldn't be searched, because Spotlight assumes one file per document. So, Apple made the amazing move of changing Apple Mail's data format so that each email is in a different file. When I imported my 29000 emails in Apple Mail to test it, I was glad that I wasn't an Apple user. No system likes 29000 files in one directory. It took 11 hours to import it, and opening the "sent email" folder was amazingly slow.
On the other hand, I am a happy Thunderbird user - and one of Thunderbird's strength is in managing huge amounts of email without a blink.
Having experienced both worlds, I can honestly say that I much prefer the open source way. Choice isn't just important: it's crucial. Trusting the natural open source ecosystem ensures that only the best applications emerge and thrive. However, I also believe that giving users a "simplified way" of doing things is essential - and that's exactly what (K)Ubuntu is doing.
It's a longer and bumpier road, but it brings better results - and it's a much funner ride.