I don't like the picture that goes with that Wikipedia article. There is absolutely nothing but the friction of the two half hitches that keeps the upper part intact. Depending on the type of rope and its surface friction, I think that top end will work itself loose very quickly.
If you follow the link to the Animated Knots by Grog website you'll see a variation where the upper part cannot come undone, other than by undoing the whole knot. The top end is then either a slipknot or a noose, or a figure-eight slipknot or noose.
On the other hand, that Grog website suggests that once under tension, you tie the free end of the rope off with two half hitches. I would never do that with anything that's under tension, preferring a slipknot with a double half hitch instead. A plain half hitch that's been under tension is almost impossible to undo. When still under tension - forget it.