This really makes me want to try Ada, if I could find a good fit for its low-level features (game development, maybe?)

The biggest thing that would make it annoying to write in is the verbose syntax--it's like the worst of Java, VB, and Standard ML. And yet, that same verbosity makes it kind of nice to read.

I think there's an inherent friction between "write-friendly" and "read-friendly" languages. It would be nice to have a language with a few different "dialects" (the way Ruby often has several equivalent ways to write certain constructs), such that a programmer could write the initial code in an extremely terse language, then run a formatter and get back a beautifully-formatted, much more verbose form of the same code.