Their articles mostly follow a dialectical format -- thesis, antithesis, synthesis, with about a third of the article spent on each one. I don't know of any other publication whose house style is so rigorous in this.
It's also highly editorialized, but very open and transparent about the positions it takes -- any bias they have is in the open, but is in the final synthesis after they've treated both sides.
It also doesn't fall neatly into any liberal/conservative divide. It tends to be socially progressive yet only interested in solutions that can be practically implemented, pro-free market but deeply concerned about externalities and the environment, pro-democracy but with hard-headed realpolitik.
Plus probably half of what each weekly issue covers is news you won't find in any other American publication, at least -- it's a global publication and one of the best ways to simply learn about the entire world's political and economic news.