There are many Mass Effect stories that challenge the status quo. Ones where they take some other organization or faction and place them in the Mass Effect universe. And some of them manage to make it interesting, portraying all sides as people.
This is not one of those stories. The UNSC steamrolls over every threat they come across and there's virtually no need to worry. The leaders of the galaxy are portrayed not as complex characters with motivations, but as grubbing, obsessed idiots who are incapable of admitting mistakes. Meanwhile the "Heroes," of the UNSC are unlikable jerks who ride around in their super-ship acting like the galaxy belongs to them.
In short, it's every bad Mass Effect fic you've ever read.