Metcals use induction heating to heat a slug of metal welded to the back of the tip. The material is designed to stop absorbing energy at a specific temperature.
This means they can pump a lot of power in without overshooting, and as the heat source is metal welded to the tip, thermal resistance is very low, unlike conventional iron which need electrical insulation between the tip and element.
The net result is very fast warmup (typically 5-8 secs from cold), and ability to quickly heat heavy copper groundplanes, tabs etc.
A side benefit is that the hot part of the tip is small, so you have a close handle-to-tip distance, without any heating of the handle, which gives good handling for fine work and comfort for all-day useage. Later models have soft rubber sleeves which are ribbed for your soldering pleasure
And yes they will still burn your finger.