I usually use those kind of flashes for background light. If you attach colored gels to it you can light the background in any color you want. Especially as an event photographer this technique is very useful. Normally you would use a on camera flash to light the persons in from of you. The background becomes then mostly dark and boring because you have to rely on the existing light sources. Using the YN460 with some radio triggers you can color the background the way you want it. The following picture shows an example. The red light on the left side, the blue one the right and the green light in the middle are the result of three remotely triggered YN460 units.
The flash unit is nothing what you can call rock solid. The battery compartment is a bit rickety. But I own those flashes since a while and they are still not broken.
You can operate the flash in three modes. The first one "M" is the normal triggering mode using the hot shoe. Mode S1 enable the optical slave mode while S2 is the optical slave mode which suppresses the triggering on the ttl preflash.
Newer models offer a metal foot. The older ones come with a plastic one.
Since I skipped technical details again, here is a link if you want more information: Yongnuo YN460. The current version of this flash is the YN460 Mark II which brings some improvements. But all the improvements increase the price too. So if you're in the market for a very affordable slave flash you might be happy with the YN460. Especially if you can buy it for 30EUR only.