It doesn't even decompile to "useable" code, but it does compile to code that will give you the gist of what what the intention was and what the actual commands are.

Decompilation to java is still a lossy process; if you want a non-lossy process you can check out APKTool which will encode/decode Smali (a Dalvik VM representation/assembly lang). But then you have to learn Smali...