So let start with the design. I have to admit that after the radical redesign of iOS 7 last year, I expected the same thing to come to the mac with Yosemite. I expected a completely flat look, very simplified -even childish- icons, with translucency in some places to give a sense of depth. Instead of that -and I am very happy for this- Apple chose to maintain the mac elegant aesthetics and make it more modern and eye appealing. A touch device, like iPad and iPhone, is a completely different use case from a desktop where the user uses a mouse and has to deal with multiple open windows. Instead of providing almost the same experience in both desktop and touch devices (like Microsoft does with Windows 8), Apple brought the same in design language in the mac but kept the desktop characteristics of its operating system almost untouched. So windows still have shadows (more subtle than before), icons are richer than their iOS counterparts and fonts are not ultra-thin like in iOS 7. System font in OS X Yosemite is changed from Lucida Grande to Helvetica Neue which brings the system in line with the iOS platform. Icons have brighter colors, but they maintain their shape variation and some light shadows. Translucency is used in sidebars, title bars and the new notification center, providing a sense of depth and context and making the whole os feel more elegant and polished. The use of white space is much less in OS X Yosemite compared to iOS, but compared to Mavericks it is much more. I do not think that the amount of white in the new system will cause eye bleeding to all of us who spent many hours a day in front of our mac display, but if you think so, Apple built in a dark mode in Yosemite, which will probably be one of the most loved design changes (especially from devs and designers).
— Nikos Maounis (@Psy2k) June 2, 2014
Except the design revamp, the new version of OS X comes with a ton of new features. And these features in most cases demonstrate exactly what Apple does. Instead of unifying the desktop and mobile OSes, it unifies the experience. The biggest improvements come to the messages.app. In Yosemite, when your iPhone is nearby, you can receive and send iMessages as well as SMSs from the built in message.app. You can even receive and place phone calls exactly like you placed Facetime calls up to now. Another great features is Continuity. With continuity you start something in your Mac (like a document, spreadsheet etc) and your iOS device is notified immediately, so with a simple swipe in your home screen, you can continue your work from your other devices. Mail.app got also a huge feature bump. The biggest new feature in mail is the built in markup capability. You attach an image, and you can add shapes, text, and callouts by drawing on the Multi‑Touch trackpad. Also using mail drop you can send up to 5GB attachments with mail. If the recipient uses mail.app, he gets the mail in his inbox with the attachment inside, exactly like before. If he uses another client, he gets the mail with a link to download the attachment from iCloud. Personally although I love these enhancements, I do not know if I will leave Airmail for mail.app after last year’s fiasco with the gmail accounts. Last but not least is iCloud drive. In simple words, iCloud drive is Apple’s answer to Google drive and dropbox. A folder in the finder that syncs across all your devices and keeps your documents organized per app.
Later this year Apple will release a new photo.app for the App with all the editing and organizing capabilities found in the iOS Photo.app. This photo.app will serve many of the duties of iPhoto, so it has to be seen what the future of iPhoto will be.
Worth mentioning is that this year Apple made the OS X beta available to all registered developers (not only those enrolled in the Mac dev program) and it will also give access to beta testers applied for the Mac beta program.
For the last 5 years Apple has focused almost on iOS, providing the mac with subtle improvements. I love that this year OS X got so much attention. Yosemite is the next step for OS X and compared to the previous steps it i a giant step forward which makes the mac look modern, even more sophisticated and the Apple ecosystem more unified than ever.
I didn’t mention anything about the new dev tools in this post, because there are so many new things for developers in iOS 8, Yosemite and Xcode 6 that they worth a separate post.