I don't know why, but I've never really liked Augustus. He was undeniably an incredibly able politician and general, but I've always seen him as being cast somewhat in the shadow of Caesar. Despite his exalted reputation, I believe Augustus actually had an easier time of taking power than Julius did, and personally that dampens his achievements for me somewhat. That's not to say that he didn't achieve a huge amount during his reign, but to me it seems like more a continuation from hi Father's achievements, and therefore not 100% his own work.
Just my personal impression on him, though.