The grand jury got all the information that was available, contradictory as it was, and came to that conclusion, so I'm inclined to assume that their conclusion is more likely than the one of Brown's defenders. Which doesn't have to mean Brown's intent had to be homicidal, merely that Wilson had to have a good reason to believe it was.
But the conclusion that American cops are killing civilians at a stupefying rate is inevitable, and regardless of the exact circumstances of this case, something needs to be done about that. Probably people picked the wrong case to make a big deal out of, but the basic point is not wrong. And I think there is more agreement on that broader point than you'd think by just looking at this case, where both sides are just staying in their usual trenches shooting at each other, disputing not just the interpretation but even the facts - it's difficult to swallow your words and change your mind on a topic as sensitive as this one, unless you're a total outsider (like me).
But that law enforcement is increasingly using excessive violence, that SWAT teams are being used for the most absurd purposes, those are points that conservatives can agree with as well, I think.