This thing is a spray nozzle on a 6-foot hose with quick-disconnect fitting. There is an in-line diverter valve that goes in-line before your showerhead, so you can just plug the spray hose in and it diverts water to the spray nozzle instead. It cost me $15 at home depot. The diverter valve is not very sturdy, it's just chrome-plated plastic. If you can find a similar product with a metal valve it's probably a good idea to go with that instead.
Living in an apartment, I don't have an outdoor hose, and the only sprayer I have is in my kitchen sink, so cleaning isn't quite as easy as it could be. All large items have to be cleaned in the bathtub. To clean my kettles, carboys, or other large items, I had to either fill them up from the tub faucet and shake them, or pour water in with a small bucket and swirl or wipe with a sponge or whatever. Carboys, corny kegs, buckets, and my keggle were especially annoying to clean. My keggle, in particular, was a real chore, and I don't feel I ever got it as thoroughly rinsed as I would have liked since I had to just gently pour water down the sides with a cup or something, rather than really spraying it.
This thing makes cleaning carboys really easy - with the water pressure I have here, the spray is very strong, and if I flip a better bottle upside down and spray straight up, the entire interior is rinsed with a steady flow of water. I fully expect it will dramatically simplify cleaning all other items in the bathtub as well. The strength of the spray (at least with the good water pressure I have) alone should cut down on the amount of oxiclean I need to use to get things clean.