My favorite change (even though it's not listed in the changelog), is that just-in-time compiled code now has frame pointers[1], making Julia code much more debuggable. Profilers, debuggers, etc. all can now work out of the box.
Extra excited that the project I happen to work on (the Parca open source project[2]) influenced this change [3][4]. Shout out to Valentin Churavy for driving this on the Julia front!