Well, it looks really great but is too hard to get to work. Errors, errors everywhere. I am not alone, check stackoverflow tag proguard.
Several years ago I used proguard without any major problems. BUT. Something really nasty happened in last several versions: with 5.3.2 I am getting: (Unexpected end of ZLIB input stream) and with version 4.4 I got: (Unsupported version number [51.0] for class format) Kind of sad that developers cant seem to get it right for VERY long time! George Matveev www.matveev.se P.S. also it is rather funny that one can not submit a bug without asking project admin! :-) Now we have to find some other obfuscator that works on Linux!
Complex in its usage due to the nature of the tackled task proguard excels at making things possible.. and comprehensive documentation helps along the way.
Easy to get started by its GUI, good documentation.
Reduced the size of my program's JAR by 22%!
I evaluated Proguard and several other commercial solutions. Proguard is one of the best of them. Only disadvantage is Copyright on Proguard code.