Today is the day, for those of you using open source graphics drivers (AMD/Intel and some older NVIDIA GPUs), Mesa 19.0 is now officially out.
From the release announcement:
I'm pleased to announce the general availability of mesa 19.0.0. We've had a slightly long rc process with 7 RCs (there should have been 6, but there was a bug in the script for pulling patches resulting in two back to back RCs). In general this release has shaped up rather nicely, and I look forward to the stable release cycle.
Of note is that autotools support is deprecated in 19.0.0, and you must now add --enable-autotools to autogen.sh and configure. If you haven't already **now** is the time to try meson, if all goes according to plan autotools will be removed before the 19.1 release.
You can find the release notes here, although unless you really know the ins and outs of graphics APIs, extensions and so on they're pretty hard to parse and since I don't use Mesa (being on an NVIDIA 980ti) I don't tend to follow it all too closely.
The gist of it, is that you should see bug fixes for games, performance improvements, new features and so on. I would suggest the Phoronix write-up for more detailed bits on it.