Yup, they make good broth, along with any browned drippings. I don't like the vinegar trick though, it used to be mentioned in a lot of Rodale books and mags as a frugal way to liberate the calcium into the broth.
Makes the broth taste funny.
I like to buy bones once in a while for soup. the really good marrow bones with some knuckle bone parts and lots of meat scraps.
Roast them in the oven first, then make soup. Chill and discard the hardened fat.
But making it with fat before defatting is a flavour enhancer. Dh adores marrow on toast, but his cholesterol won't stand it.