Broken Base: The series's fans love the new ideas presented by the Mirror Universe and feel the story potential and characters are great twists on the classics. Non-fans feel the series is a negative example of Running the Asylum, and contains more winks at the franchise than plot.
Ultra Magnus was locked up in his universe for trying to usurp Optimus Prime, getting his face ripped off in the process. He and several others travel to Earth, where he assimilates numerous Autobots into the Junkion hordes, resulting in them becoming mindless slaves and dead in all but name. After that, he proceeds to set up a plan to take rarified energon from Earth with his sword and destroy it. His plan is foiled when a shield is placed around the Earth, but his real plan was to cause the death of the entire universe. Even the normal Decepticons turned against him, as they wanted to be the conquerors, and were appalled when they realized the extent of the damage.
Thanks to his Ascended Meme status and general adorableness, Ravage gained a lot of fans. Pictures of him waving with variations on his Catchphrase "Can U C me totally waving @ U!!!!!!" are common, and often even people who don't know much about the rest of the continuity will still know all about him, despite him being a very minor character in the actual plot.
The articulate criminal genius supreme Grimlock from the original comic was just part of the April Fools joke taking the whole Mirror Universe concept to its silly extreme, but he proved so popular that the Grimlock from the actual comic eventually underwent an upgrade to become just like him
First Installment Wins: Since the original comic is (so far) the only story available outside the fanclub, not only is it the only part of the universe most people know, but many folks also don't even know there were more stories.
Ho Yay: Starscream's behavior around Megatron tends to vacillate between "fussing mother hen" and "teenage schoolgirl with a crush".
Unexpected Character: Not Optimus himself, but nobody was expecting Unicron to reformat him into Nova Prime, and especially not this ◊ Nova Prime.
The Woobie: Sari Sumdac's Shattered Glass counterpart comes off as very sympathetic due to her father being abusive towards her and using her as a weapon.
: The Fallen escapes from his defeat in an undefined universe and retreats into the Shattered Glass universe. There, he discovers the nature of negative-polarity universes, and plots to conquer them all. Deceiving the Underbase staff into serving him, The Fallen has them build a portal to the multiverse that requires "components" to work, said "components" being organic brains in cybernetic bodies, while also forcing his zealously loyal follower Sunstorm to use his fire powers to thaw him out from the ice that freezes him, apathetic to the fact that using too much power will kill Sunstorm. Under The Fallen's servitude, agents of the Underbase deceive organic aliens of all kinds into becoming "components" under false promises, and then use them as batteries, painfully electrocuting them in the process. When Cyclonus, Darkwing and Crasher arrive to find and save their human friends, The Fallen attempts to kill them, sparing them only because Crasher's unique brain allows her to be used as a "component". Once the multiversal portal was ready, The Fallen sends his servants to inspect the universes it leads to, and if they're not negative-polarity universes, he demands the portal be shut down until the next trial, permanently trapping his servants on the other side and showing no concern for their lives even if they're killed. Even in the Mirror Universe, The Fallen proves that he will remain an irredeemable monster whenever he manifests himself in the multiverse, appalling even his own troops.
