I've had a Weller Portasol butane powered iron for almost 25 years now. I used to use it constantly when I was repairing drive-in theater speakers "out in the field" back in the 1990s. With my car loaded up with speaker repair parts and being hundreds of feet from a power source, the butane iron served me very well. I still use it once in a while to solder on a wire on a broken flipper coil and things like that. Butane irons can be used on circuit boards, but I don't recommend it. The reason being is the hot exhaust gasses which shoot out the side exhaust ports of the burner chamber. You can scorch or burn the circuit board.
The iron heats up fast and cools down faster than an electric iron. There is a knob on the bottom of the iron that regulates the flow of butane when in operation. Works like a heat control potentiometer on an electric iron. So, in essence, you can have the equivalent of a 20 to 45 watt electric iron. There are several sizes of tips available from big fat tips (for coil lugs) to tiny ones for pc boards. When I was doing drive in speaker repair, I was using the iron 7 days a week, about two hours a day, I got about 3 months out of a tip before I had to replace the tip.