3. Pros and Cons

The main argument in favour of LED spotlights is their energy consumption. Compared to a halogen spotlight of similar light yield, an LED spot will use only a tenth of the energy, and this is set to become even less with development. LEDs are extremely durable, with up to 50,000 hours of operation indicated for some models. This leaves all halogen spotlights in the dust. Since there's no filament moving about inside, LED lamps are less prone to suffer damage while being put up, taken down, or transported. In addition, they do not require additional dimmer switches and periphery elements such as heavy-duty cables and plug-in boxes. Furthermore, LED lamps always include strobes. If they feature individually controllable light pixels, you can even use the lamps to create images or play videos - but this is only possible with special LED lamps.
LED spotlights do not emit heat, and this is a noticeable relief on stage: artists sweat less, and the equipment is also not exposed to additional stress caused by high temperatures. Colour filters can be done without, since the colours are mixed inside the spotlights.
Many models also feature a master/slave mode. In combination with the stand-alone modes which are often very attractive, this means you can achieve beautiful effects even without a light desk, particularly if you can program scenes directly on the lamp.

Multiple coloured shadows are unavoidable at the budget end of the spectrum, and with certain LED array types. These can sometimes interfere. Even more expensive devices may cast coloured shadows, but with those devices the light will have mixed evenly within a short distance, and the colour shadows disappear.
The LED light spectrum is not as even as that of a halogen lamp. Depending on their characteristics and construction type, diodes feature strong narrow monochromatic peaks in thre colour spectrum. This distorts the light impression compared to halogen lamps, which often seem to emit warmer light.