I began the game fully intending to free Skyrim from Imperial control, but an open-mind has led me to supporting the Empire.
Unsurprisingly, the only people who have anything good to say about the empire are the Imperials themselves, and those who have something to gain through Imperial rule
Spoiler (The Jarl of Whiterun, for example).
Beyond that, for all their talk of wanting a unified empire to fight the Aldmeri Dominion, they do nothing but make concessions to the Thalmoor and act as their enforcers.