Because there really are very few good liberal/progressive publications available for the Kindle (or anywhere, for that matter), I subscribe to/support two "political" Kindle periodicals, The Nation and DailyKos. (For the more right-wing fare, I go read it free online.)
The Nation's issues are well organized, sometimes thematically linked, and the articles well written with ample depth. I find myself learning about global issues that normally are not even touched on in the usual "lowest common denominator" fare on TV. Happenings in the arts and sciences are also covered.
The Nation comes out once a week, which I find to be a good rate of publication for a magazine of this type. You don't get the breathless "breaking news" type of reporting (a la Wolf Blitzer) in The Nation, which I find refreshing, but the issues are current and usually of considerable importance. The editors have time to be editors and the writers have time to do their homework. It's a more measured, intelligent approach to the world than we've gotten used to with cable news and screaming-head blogs.
I do not find The Nation to be all that left-wing. On the contrary, I find a balance of perspectives from left (mostly left-of-center) to center-right. Importantly, there are no "Screaming of the Extremists" portions. There are well-articulated viewpoints and the occasional intelligent debate. I'd like to see more of that tone in our general discourse.
The Nation works great on the Kindle, and I find it very easy to get around each issue. So far, I have not encountered any typos either! I appreciate the work that goes into each issue.