I've seen quite a few Chicago MAPSS post and as a MAPSS alum, here's some thoughts: Overall I came out with mixed feelings about it. I'd recommend it if 1. you get at least 2/3rd tuition funding (Or you are rich enough that finances aren't a constraitnt), 2. you have a good idea of what gaps in your academic training you want to fill in and 3. have some sense of what you want to pursue at Chicago in terms of MA thesis research. Otherwise, you will go in confused and come out more confused after 10 months. Contrary to what MAPSS admin may tell you, there isn't much institutional support; the program itself has no structure; so it really boils down to how proactive you are in terms of thinking about your MA thesis very early on, finding a good faculty to work with, tailoring your course selection keeping in mind PhD apps etc (For some of us, 9 months is just not enough to figure this out well). Also, quite a few of us treated MAPSS as some sort of an extension to our undergrad (like I did to an extent), which meant that MAPSS didn't end up really adding much value to our resumes.
That said, my life post-MAPSS turned out just fine (a good research job at a reputed intl think tank) and a now T10 offer, but at least in my case, I doubt if MAPSS really added much. And don't go by the PhD admit statistics they cite in their website (90% admit blah blah doesn't account for selection and we don't know the counterfactual ¯\_(ツ)_/¯).