Many native extensions just work with TruffleRuby, I'd estimate even the majority of the popular native extensions just work. Performance of native extensions is not always good, especially if they do a lot of back and forth between Ruby and native.
To give one example, DB adapters work just fine.
That's awesome news, and I can't get a more authoritative source than you! I'll do some tests and update my assumptions :-) I really do wish I saw more blog posts and things about TruffleRuby, but maybe that is just a sign I should make the effort myself.
Since I have you, if you could humor me at all, what do you think the biggest current sticking point to average Rubyists just flat out switching to TruffleRuby is nowadays? Or isn't there one?