I wasn't sure what to expect when I first started watching. Heck, my only exposure to the show before actually seeing it was the joke 4kids trailer someone linked. I liked the artwork enough that I watched the first three episodes. And after business picked up in Episode 3, I went ahead and watched the rest.
I fell out of anime for a while, with very few exceptions, mostly because most shows I tried fell into some boring, predictable format with characters I just didn't give two fucks about. KIll la Kill changed that. The plot was interesting, even before the reveal hit that Satsuki was plotting against her mother the whole time. And the characters were characters I liked, that I wanted to root for.
Going back to that reveal, it floored me. The second Satsuki stabbed Ragyo in the back, I was shocked, sitting in my seat, hands over my mouth and nose, for like five minutes. In hindsight, I probably should have seen it coming; I thought it was weird for a show like this to make me actually CARE about the bad guys without having something like this penned in the future. Then again, no other anime made me care about the bad guys, so perhaps that's why I was so shocked.
On the flip side of that coin, the villains, I REALLY hated. Nui and Ragyo are indeed monsters of the highest order, and I cheered when Ryuko kicked their asses. Slicing off Nui's arms, in particular, was awesome. Hell, all the main characters had varying levels of awesomeness and badassery. While I had a girlcrush on Ryuko for most of the series, Mako is my favorite character. Almost every time she was on screen, I was smiling. She just made the show sooooo much better.