Seriously. Yeah, I'm writing two posts in a row about the same thing, but Girl Genius is Just. That. Awesome.
It's got mad scientists. It's got robots. It's got constructs. (Oh, man, does it have constructs.) It's got wacky Germanic accents, a circus, lunatic heroes, hats, plumbers, and a talking cat.
Mostly, what it's got is win.
All the characters have clear, unique voices. I can hear these people, the way they talk, and they all talk in a distinctive way. There's heavy use of dialect, which is normally a bad thing, but in this case it's cool. (My theory is that it's a large group of characters that all use the same dialect, so you don't have to learn a different one for each individual character. And it's very funny, the way they talk.)
It also exercises my plot sense, (like spider sense, only for plot rather than danger) in an extremely satisfying way. Everything that happens feels right, but it never feels boring. It's always, "That's exactly what has to happen! Awesome!" and never, "Gee, I kinda saw that coming." It escalates a lot, with plot twists galore, but it never feels cheap. It's exciting, and frustrating, but in a seriously awesome way.
It's got major character death that doesn't feel like a lame plot device! It's crazy!
Yeah, so, read it. NOW!