Midna is without a doubt my favorite assistant. But the abhorrence many players hold toward her may have derived from the contradictory setting she was placed into. To put it simply, she was out to topple Zant for usurping the throne from her, and exiling her. Her ultimate goal was to retrieve the Fused Shadow, use the Mirror of Twilight to reenter her realm, and destroy Zant right then. This is likely what would've transpired had it not been offset by Ganondorf's sudden appearance. Nintendo backed up her past story with Zant perfectly, but her character development seemed shortened with Ganon inserted. There was no driving force to go after him, really, once Zant was defeated.
Nonetheless, she carried over from one behavior to the next--from arrogance to obligation, for example. Even by Ganon's sudden drop into the story Midna knew what had to be done and acted on it. She can't be faulted for only wanting to restore peace and balance between her people and the Light World. You can tell this is true since she shattered the Mirror, ensuring that the two realms never fought again.
