For those of you who find NEWS files a little bit TL;DR, Bozhidar Batsov has a nice post that discusses the highlights of the Emacs 27.1 release. It’s a good way to see what’s new and important in the release. If you haven’t upgraded yet, the post should be helpful in your evaluation of the pros and cons.
Batsov feels that most people will find the JSON parsing and associated LSP support the best part of the update. I like support for arbitrary sized integers and the use of lexical binding by default the most. That’s probably because I hardly ever interact with JSON so I’m sure my preferences are a minority opinion.
I’m at one with Batsov in being glad that the developers can now devote all their energies to Emacs 28 with its native compilation. That, I think, will be one of the most significant changes to Emacs in years. It will be much like SBCL Common Lisp and other major Lisp compilers: write in Lisp, have it compiled to native code, and run at speed.
In the mean time, Emacs 27.1 brings many outstanding improvements that will enhance the Emacs experience. These are truly exciting times to be an Emacs user.