They are very comfortable to use, but they cost double the energy. If you're still on coal power, you'll use twice the amount. If you pay more e.g. eff modules, or have the power to spare, yea they are great.
Once I had about 1k solar panels and three nuclear reactors with self-perpetuating enrichment, I shut down all the efficiency module production, ratcheted up speed modules and beacons, and went to town.
Even if still on coal power, I think the tradeoff of not needing to run coal belts everywhere makes them worth it
Yes, but you can finally stop using coal in smelters so more is available for power generation.
well, it's more boiler power. and ... energy in Factorio is just accounting. I switch to light oil based solid fuel pretty quickly, becausing priority splitters making replacing coal with solid fuel easily. i consider 10 light oil to cost roughly 8 crude with advanced oil processing, and getting 5 crude per pumpjack scond is pretty easy. it costs 72 kJ to extract that crude oil, 134.4kJ to turn it into light oil, 105kJ to turn into solid fuel, for 311.4 kJ to make solid fuel (239.4 from oil refinery /chemical plants). Compare to 270 kJ to make 3 coal. Basically the same, for 3 times the density, for.a resource that's a lot harder to run out of. And even if I do, I likely won't run out of coal at the same time, so my factory can limp while I address coal/crude oil shortages.
I mean, coal power is a short stage in unmodded game, it doesn't really matter