It's not immediately obvious, but what class library does it work with? Gnu Classpath? Something else?

If this doesn't have a good deal of the rest of the built in Java ecosystem, then does it have much value or usefulness?

Does it have a possible advantage without a JIT, like being able to run in constrained amounts of memory?

This is amazing! This would be very useful for people (esp. students) who want to get to the core of the internals without getting bogged down by details and optimization.