Although Go was initially marketed as systems language it more often than not eats into Python's market share rather than C++ or Java's - at least in all places that I've seen it 'in the wild' (eg. saw that 1st hand at Google, read about that at Dropbox). Coming from professional Java or C++ development Go feels lacking but it feels like an incredible power-up when it replaces a piece of Python (or Perl, or Ruby, I guess...)