Locations isn't all gone. I have locations left over from a previous OS and I still have the Locations menu item in the apple menu.
What's gone is the interface for creating, editing, and deleting locations. For that you can thank the moron who decided to rewrite System Preferences into System Settings but didn't demand that all functionality be replicated in the new code. As someone else mentioned, the CLI tool for this still exists, fortunately.
There are *so many* bugs with the new System Settings. The worst, for me, is that you can't edit wifi network aliases. When you try, it actually shows you the settings for the primary wifi interface. You can get around this from the CLI, but it's a real PITA.
There are also a zillion little new bugs in Mail.app. It's really crazy - it's like they have someone on staff whose entire job is to introduce stupid little flaws in that app. And they've had that job since Snow Leopard. :-(