The OS for all Macs is also out. Lots of little nuggets of gold to uncover.
First, it is okay to upgrade? There are no major problems. One caveat is if you use some sort of specialized software such as accounting software or Adobe Creative Cloud. Make sure to check for any compatibility issues. Otherwise, go for it.
This release will not significantly change the way you do anything. One of the big changes, if you like the idea of talking to your computer, is the integration of Siri. Siri is now available on the Mac for you to ask questions, run programs, etc.
As for me, I have boundaries, and when I choose to speak to the inanimate objects in my life I prefer that they don’t talk back. But I do fully respect those who choose either through choice or necessity to fully embrace the power of our future overlords.
More seriously, with the new OS, Messages contains the same enhancements as the iPhone.
iCloud has a big upgrade with a new feature that makes it more like Dropbox. You can choose to have it store your Documents folder and Desktop in the cloud. This has some pros and cons. On the plus side, all your documents will be stored locally and on iCloud. On the minus side, the local documents are no longer stored in your Documents folder but in a obscure location on your hard drive. The way to access these files is to open them from iCloud->Documents. And unlike Dropbox, this new feature is all or nothing. You either store the entire Documents folder or nothing.
Another plus, if you have multiple computers, using this feature will keep your Documents folder and your Desktop in sync on all your computers.
You can read more about iCloud here and here.
If you have concerns about cloud security you can read more here. The biggest vulnerability of cloud storage is your password. Make sure it is unique and hard to figure out.
Big warning: if you decide to try this feature, use it for a while, decide you don’t like it, and turn it off, be very careful. It is very easy to delete all your files. You must manually save the files from iCloud back to your hard drive before turning off this feature.
However, know this: iCloud does save deleted files for a while. So when you discover that they are gone, they can be restored.
iCloud has another new feature to optimize your hard drive. When you start to run out of space, iCloud will determine what files have not been used for a long time and move them from your hard drive to iCloud to free up space.
If you decide you really don’t want to upgrade here is how to turn off the automatic upgrade.
Again, lots of new stuff. Have fun!