I did my MSW at UChicago, where i took classes with and got to know several MAPSS students. There's a ton of variance in how useful they perceive the program to be, and how happy they were overall with their decision. I think it depends largely on faculty you take classes with and work with, as some profs seem to be much more helpful with LORs and thesis mentoring than others. It has a reputation for being a huge cash cow for the U of C, and I know that there are consistently several students every year who still fail to get PhD offers. Personally, I would weigh very carefully the financial aid offer they gave you, how much debt you would need to incur, and how good you've been, generally speaking, building relationships with profs in the past.
I need to also add that, from what I've heard, no one in the program reapplies during the first quarter-- they all wait until they've graduated. At this point, you'll already have a thesis in hand, and (hopefully) professors who know you pretty well and can vouch for you in LORs.