I am surprised and impressed by how well everything runs, even on the older machine. I tested High Sierra on a new 13-inch MacBook Pro and on my workhorse machine, a 13-inch MacBook Air, complete with all the apps I've accumulated over the past few years. That said, there are plenty of changes you can see too, most notably in the substantially updated Photos app. Apple does a superb job of making its new APFS file system fully compatible with the old one, so any app that can run on an HFS+ disk will also run on an APFS disk.
The biggest changes from macOS Sierra are invisible technical changes that go to the heart of your system-the file system that underlies everything on your disk. It lets you use your system exactly as you did before, without climbing a learning curve.
High Sierra, Apple's newest version of the macOS desktop operating system does exactly what an operating system upgrade should do: It makes your system faster, safer, and more reliable, while adding some welcome but unobtrusive conveniences.
