The housing is high quality, well polished, and looks good. I expect it will last for decades. The lights do not have a replaceable bulb, but contain a circuit board with surface mounted LEDs. If anything ever goes wrong with the board, the entire light is toast, even though almost all the cost is for the stainless steel housing.
When using 12 V, you have to use DC; the light cannot accept 12 V AC. I added a small bridge rectifier and capacitor (which fit inside) to use them with AC. Note that this requires some soldering skills.