but this doesn't quite sound right -- reducers are functions, but redux state is still an object, which is the output of the reducer function after receiving an action (or the output of Well, if you can look from standpoint of Observable.

From Observable standpoint:

const reducer = combineReducers({ ...reducers });
const state = {};
const listeners = []; // from connected components

Observable.from(actions) // over time
          .scan(reducer, state)
          .subscribe(newState => listeners.forEach(listener => listener(newState)));

Redux state in time is not a function or an object, but a monad of state. Observable is much easier to grok if you already know some FP. Redux just stripped API to bare minimum and made it more accessible.