My understanding / guess is that it works for almost all production use perl scripts - bad luck for a few esoteric ones.

My understanding is pretty much the reverse - it works for a few tightly-constrained scripts but not for the majority of general-purpose code that I would use on a daily basis.

Why is there no buzz about this solution? Is it too good to be true?

See above. The constraints just now are too heavy for most users to get a benefit from it. That said, I think there is a buzz, just not a huge one. I've not attended one of Will's talks yet but (at least some of) those who have say they have been well received. It seems very likely that the more interest it generates, the more people will work with it and then on it and so the pace of development will pick up and more constraints will be lifted resulting in wider use - a spiral of win.

You might consider the similar low levels of adoption of Perl6* at present. There is a lot of buzz about that language too but I'm not yet convinced that it will break through. If I had plenty of free time to devote to either project it would be RPerl rather than Perl6* which would get the attention.

Other opinions are available :-)

* 2019 note: now called Raku