I think the only thing to be said about BP&W is that the initial set up is quite important - get someone who has dived the system to help if at all possible. Once the set up is right, there is very little needs to be done to it afterwards - even when changing between wetsuit thickness's or between drysuit/wetsuit.
Neilwood is correct. This is probably the only downside to a BP/W. It can take some time to move things around and adjust the harness to fit you. Once you do though, it's great. If you go with the "deluxe" style harness with multiple webbings, pads, etc., the set up can be rather intensive. A single web harness is easier to set up and is really all you need.