I think target audience is folks who're mucking around the low-levels using javap, proguard, Jconsole/visualVM tools (jmap, jstack etc) and other diagnostic/disassembler tools like that for benchmarking/tuning, picking hotspot command line options, looking for malware, shoehorning into android etc. Javap is pretty well documented, you could start there.

this is good, about byteman, JRebel, tools like that

http://arhipov.blogspot.ie/2012/09/javazone-2012-taming-java...