I upgraded on my MacBook Pro about 4 weeks ago. There are new features, two that spring to mind are stacks, where work is stored in , well stacks! Eg one on top of the other on the desk top. When you click on the stack is breaks down into its elements.
Second is “ dark” this is a screen effect that turns everything you are not working on dark. Its a bit gimmicky, but I am using it.
Stability wise, its like every MacBook upgrade I have done it is stable and no bugs.
Hth
Steve