While fun at times, there's really not too much to say about Game Change other than the fact that, yep, it sure was a movie. It doesn't bring anything new to the table and mostly just exists as a jab.
The casting was downright inspired though. Outside of a couple lines here and there where the Boston accent slips through, Moore is indistinguishable from Palin. Harris is spot on as McCain aside from the voice, but with the appearance and mannerisms as perfect as he had them, it's hard to fault that.
If there's any one reason to watch, it would be Harrelson. It's one of those roles he'll show up in every couple years just to remind Hollywood that he's an incredible actor with immense range. Shame he doesn't do it more often.