I’ve been using the Black Rapid RS-7 Camera Strap for about two years. The Black Rapid, similar to other slings on the market, is a cross body strap rather than a typical neck strap. The sling style helps distribute the weight of the camera across your body. Black Rapid offers a few different styles of sling straps and some attachment accessories as well. They have a double strap that would work great for wedding photographers. The Black Rapid Curve or RS-7 is the basic strap and now comes in five colors. It will run you about $60.
I’ve found the strap to be most useful when shooting events and traveling. It worked out perfectly on my European honeymoon adventure. The camera slides down the strap to rest at your hip when not in use. The camera can be locked in place using one clip in front of and one clip behind the camera keeping it more stable while walking. If you’re shooting, I suggest keeping the back clip locked to keep the camera from sliding back too far, and it (kind of) helps keep the shoulder pad in place. If you’re in the studio, the strap is just going to get in the way plus it occupies the tripod socket. I frequently switch between a hand strap and the Black Rapid so I find it annoying having to attach and detach them from the tripod socket. You can purchase a tripod modifier (for certain brand tripods) for the Black Rapid fastener, but it’s more of a band-aid than a solution to me.
The Black Rapid connects via a metal fastener to the standard 1/4″-20 tripod socket on the camera body. It’s important to check that the carabiner is securely locked throughout your shoot. It will loosen over time and you want to avoid that awful, camera falling in slow-motion toward the unforgiving concrete sidewalk moment. The one point connection helps eliminate some of the bouncing around; however, the camera still bounces on my hip and flops around when I bend over. It’s easy to forget I have the camera on since it is pretty comfortable during normal wear, but I end up banging the camera on something when I bend down to get something out of my camera bag or do my mid-event squats. (I totally don’t do that.)
I did have a big fail with the Black Rapid strap though. I was shooting an event with an on-camera-flash and a diffuser. Some time during the evening, I must have had the camera resting at my hip and the modifier fell off. I contacted the venue afterward but no luck. $60 down the drain. I don’t recommend the strap when using a flash. It doesn’t distribute the weight as evenly and, well, you could lose out on some gear.
TL;DR: The Black Rapid is a nice quality, comfortable strap suitable for certain occasions. Once you get used to it, you’ll know when it’ll work for you and when it won’t. It may not be perfect, but it is more comfortable than a traditional neck strap.