On the civilian side, you get to feel like you live in a goddamned war zone, with the police as combatants. It's not a nice feeling.
My own approach is to treat cops as large, gun-wielding wild animals: maybe they'll be fine, but in any interaction there's a chance they'll fuck up your life permanently. And that's a direct consequence of having police on 'war footing' with the community, where the default reactions to problems are either violence or long-term imprisonment. And the ethics of this extends beyond my own interactions: if I see something illegal happening, calling the cops means putting people in extreme danger. As a result, I'm not going to call the cops for anything less than assault. Thus, police militarization works against actual enforcement of the law, because it estranges police from the population. (For a whole lot more, go listen to season 3 of the Serial podcast...)