Slid points as to issues. I think the benefits still trounce the negatives and we can certainly try to neutralize the negative points. A few things.
Cameras should run 24/7 when released to an officer from equipment, no exceptions. If it records the sounds of a big 'ol dump, big deal. Not having evidence because an officer forgets to turn it back on (which is super easy to do) puts both officers and civilians at risk for no good reason. Lots of us are on camera at our jobs, and still get paid a lot less than cops do. It's really not a big deal to reign in one's behavior for a shift.
Parties in the recordings should have the right to refuse to have their image and voice publicized until convicted of a crime pertaining to said video. In other words, if anything is released to the public, if the people in the video don't consent, their image must be blurred and voice altered before being released to the public. Pretty standard stuff.
Police should be given the same privacy rights as citizens in videos, and they should have an option to request obsfucating their likeness until convicted of a pertinent crime.
There should be a timely request process for video evidence used for defense purposes. The system may be open to abuse from request spam, but all documenting systems have to deal with this when legal gets involved.
Officers should not have any access to the technical side of the recordings, ever, at all under any circumstances. All editing and handling of data should be performed by a third party who are in no other way connected to the police department. This is to protect police from accusations of tampering. It's similar to blind accounting, securing through compartmentalization, reducing the risk of conspiracy.
I think with a system like that in place, flaws not withstanding, it could be much much better than it is today.