I don't think he's actually written much in the language (which is somewhat understandable, since the damn thing isn't implemented yet), and that's causing problems because he hasn't realized how annoying simple things like his any statements become.
Yeah it'll be interesting to see how it goes. I'm actually more favorably disposed after the thread on the list. His motivation is a reasonable one: to make the static shape of code more closely mimic how it looks at runtime. This requires constraints so it feels kinda wild and whacky. But I'm glad somebody's trying these ideas.
Running statements in reverse order isn't such a big deal. Concatenative languages seem backwards, and even preorder is kinda weird at the start.
The best new languages require so much tolerance to the bizarre that it hurts. Alan Perlis said, "A language that doesn't affect the way you think about programming is not worth knowing." I just realized he didn't say, "A good language.." Potential dead ends can be worth knowing as well.