Well, it's complicated. The original jdk compliance tests are notoriously hard to deal with. Currently I parse nearly 100% of positive testcases from JDK 7 test suite (in one of Java 7 branches) but I only have several dozens of true end to end tests (build .java with jopa, validate classfile with javap, run classfile with javac).

So, I can't tell how good it actually is but it definitely handles reasonably complex source files with generics (something the original compiler was unable to do).

The actual goal of the project is to be able to build at least ANT to simplify clean bootstrap of OpenJDK.