It's great for privacy, even better for security. It takes about two to three years for it to mature into a fairly impenetrable hedge. The first year nothing much happens, but by the end of the second summer you wouldn't want to walk through it. By five years you can't see through it during the summer, and you'll have trouble seeing through it in winter.
As a bonus, I've noted that hummingbirds like to nest in it. The brambles seem to appeal to them. Rabbits and similar critters use it for cover. Dogs can't really get through it.
While a fence isn't mandatory, the shrub likes to climb stuff and will take right to the fence. It isn't what I would call invasive, although it will spread slightly it doesn't try to take over a yard when there's nothing to climb. Like you, we had some neighbors that were very picky about their own back yard and they loved it as it provided the perfect backdrop for their yard. We just let it grow on it's own, but these people kept it trimmed and cultivated, and as a result the stuff grew to about eight feet in height, and the blooms were sweet smelling.
About the only real downsides are that it can be tough to start. It's sensitive to drought and monsoon conditions, so we had to replant in some cases. The other thing is that when it's fully grown and you have a thick hedge, you really cannot get through it. Horses, for instance, cannot force their way through it. Neither can dogs. Trying to create a gate way or something would be a major job and likely take all day.
We planted ours so long ago I couldn't tell you where to get the plants. Ours were a foot or so tall and we planted them a few feet apart.