I bought two of these for use on a mirror ball as part of my mobile setup. Now, I know you could argue that I should be using four, however, given the strength of the these, I don't think it would've made much difference.
The positives are that they are solid, the beam throw adjustment is handy, and they are cheap.
The negatives however are, the cables are drastically too short, even for a permanant install. They had to be altered with an IEC C14 termination. the focusing range of the lens allows for no more than about 3-5m before the beam reflections are blurred. Most critically of all though is, the power output/luminance is just not good enough for a room larger than 5msq.
These are fine and adequate, for a small function/conference room, anything larger, spend the extra for higher wattage.