Acceptable Political Targets: Shin pretty much bashed Republicans every chance he got. Since most of the run happened during the George W. Bush years, the bashing was near constant, to the point that the Bush Administration became a recurring villain.
Archive Binge: Oh yes. Not to the extent of stuff like Sluggy Freelance or Homestuck but you'll definitely end up going on one if you want to understand all the in-jokes, running gags, and bits of continuity. To give you an idea, the comic is broken up into seasons. There are 37 seasons.
Continuity Lock-Out: Not much of a problem with the one-off gag strips or short 2-4 page storylines, but can definitely occur during the actual plot-driven story arcs.
Creator Backlash: Not against the comic itself but against the Kaiju Girls gallery. Word of God admits that he only hosted them in the first place to help get more traffic to the site. Since most of the contributors to the gallery had already disavowed their work and the comic was clearly able to stand on it's own, he eventually just deleted the whole thing.
Ensemble Darkhorse: Mazinger Z and Great Mazinger. The former once let on that he's kept in the comic because his impressive articulation contrasts well with the single-vinyl-hunk majority of the Kaiju figures.