No, it isn't. PyPy code is very poorly commented and documented, there's a lot going on inside the same codebase. So far, it feels like the only people who hack it are the ones who wrote it. This needs to be sorted out before we see mass adoption.

readability is probably not the right term, but I think he means easy to understand. Doesn't matter how elegant PyPy's code is, it'll surely be more complex than an straight forward interpreter.

I'm saying that it's big. Specialization requires special cases, which require more lines of code. One should be able to reason about the entirety of a Python implementation, and that's very difficult to do for PyPy.