OS News, one of the websites which covered BeOS pretty well in its heyday, is still going strong. And it's got a good summary of this release: https://www.osnews.com/story/140746/haiku-r1-beta5-released/

I remember running BeOS on a Power Computing PowerCenter machine (a Mac OS licensed machine for those too young to remember) and being super impressed. This was the Mac OS 8/9 era and BeOS immediately felt modern. The teapot demo running while maintaining system performance was neat party trick.

Find the release notes with screenshots here: https://www.haiku-os.org/get-haiku/r1beta5/release-notes/

It's so cute. Does Firefox work on it yet?

Yes, there is some really good progress towards a out-of-the-box working Firefox on Haiku. https://discuss.haiku-os.org/t/progress-on-porting-firefox/1...

That's great news. It looks like we still have to build it from source but I imagine a package is coming soon.

Could anyone who's tried installing it on a 2015 MacBook Pro give me some feedback - will it work?