I feel that when humans reach the level of interstellar travel, the Mirror Universe is what we will see.
I too wondered how the Terrans manage to get anything done at all with the backstabbing going on. Then again, almost the same thing is going on in Congress (minus the literal backstabbing of course.)
Phlox's "would you kindly die" line was funny. Mirror Archer going nuts and seeing the prime version of himself mocking him. Mirror Hoshi putting the -censored- back in Hoshi (not my words, it was actually mentioned by the cast.
)
I was glad the show had at least one arc featuring the Mirror Universe. Though I would have liked to see the Earth-Romulan war during the series instead of the temporal cold war that turned into the Xindi arc.