This stuff may be an old stereotype, but it's not that great of an option. The main reason being oil-based lubricants are really difficult to clean up, and you have a risk of bacteria growing on the residue. Because of this, I've never even tried the stuff, so I can't comment on the texture or ability to lubricate.

Soap seems to improve the slipperiness of water, but it's otherwise not very effective. It has a tendency to fade away quickly, so that you have to keep getting more. Worst of all, though, is that it'll burn if you get any inside your eurethra, and that burning can hang around for an hour or two.