We bought 6 of these a few years back. We use them in our theater for every now and then. I like them because they are light, easy to tug away and no nonsense. No more heavy cables to pull around. You bring the dimmer to the bulb. Last week one broke down so now I'm ordering the same again. For this price...
Downsides: when the bulb breaks, it usually takes out the fuse as well so you need to get up to the truss to replace. It also doesn't filter out voltage jumps, but you could hardly expect that in this price range.
So: for pro's? No. For an occasional user who is budget minded and likes to be flexible in his setup: definitely yes.