At it's best, it can be a very good thing.
In larger towns, cops often become these faceless beings who cruise around looking for trouble.
"Community policing" when done right means that individual officers cover as small an area as possible, and get to know it by getting out of the car (or off the bike or whatever) and talking to people, finding out what's REALLY going on, and what problems are serious versus worthy of only a wink. And better yet, they can get a sense of what trouble is brewing and needs a firm hand before it blows up.
Let's take one example from my own past: some dude has a pet ferret in Calif where they're illegal, and takes it to play in the local park.
Under the "standard model", cops drive by, spot an illegal critter, make a bust.
Under "community policing", they might already know that half the kids in the neigborhood have played with the fert, it never bit anybody, the guy that owns it has even been in local businesses and neither him nor the skinnykitty ever caused problems. So they ignore it.
That's just one example of what's supposed to happen.
On the flip side, the community beat cop has an idea of which kids are actually trouble and which are just being kids, and can stop real trouble (gangs/drugs/etc) before it starts *without* coming across as "harassing all kids" and breeding a whole local generation that fears the uniform.