The Steam reactor itself is still the same chocohead. Only difference is that you cant do unstable ones and you need to provide coolant.
But not much more was added besides that in the reactor itself.
Thats why classic made it its own concept. Steam vents that need to heat up to produce steam. The hotter they are the better they perform.
The reactors heat tick runs also 20x faster, which adds a high risk to using it and pros can do so much more with it, because they have specialized components that act differently in the reactor and managing the inputs & outputs become a task instead of blindly filling & emptying the rods & coolant.
Steam reactor nice idea but a boring implementation. (That only counts the reactor itself not the outside stuff)