100kW can raise the temperature of 1L of water from 20C to 100C in 3.34 seconds. It's enough power to brew about 300 shots of espresso in 30 seconds. That seems like a lot to me.
1 kW is a lot if you put it into a small enough space. Or even 1 W, as my background in electronics design has shown me on occasion.
Of course, the title calls it a fission reactor and a 100 kW one would not be much. Would charge an electric car pretty nicely, though. Or make some mean espresso.
The thing to remember with this bad boy is they've got active gamma emitting fission products floating in it and (when it could still go critical) fast neutrons. Not s something you want to brew your coffee in, even without the heavy metal poisoning uranium oxide could give you.
What's cool about this reactor is it was doing something that we generally can't do too well. Unenriched uranium reactors tend to need heavy water or graphite to slow down the neutrons from fast to thermal to keep a reactor critical This guy used ground water.