It is truly an interactive ("online") environment. Almost everything is typed and through introspection the shell can offer very rich auto-completion hints, without needing tedious scripts such as those used by bash/zsh.
Quick example:
get-<Tab> cycles through all get-[whatever] commands, as you'd expect. get-certificate <Tab> cycles through all parameters available for get-certificate get-certificate -ErrorAction <Tab> cycles through the list of valid values for ErrorAction (there's like 6 of them: stop, suspend, etc.)
It is also highly standardized, there's a set of "verbs" allowed so that it's much easier to find something since everything is in a certain category (https://msdn.microsoft.com/en-us/library/ms714428(v=vs.85).a...)
It has its bad/ugly bits, but the principles are quite solid. In many ways they are what I'd expect if Richie and Thompson would have designed Unix in a modern environment (i.e. not an environment where the output of your commands would be printed :) ).