a user interface. It is intended to be the simulation engine around which a third-party interface can be wrapped. Inputs and outputs are simple ASCII text that is decipherable but may be best left to a GUI (graphical user interface). The current known third-party interfaces/tools can be found at https://www.buildingenergysoftwaretools.com/?keys=EnergyPlus
a life cycle cost analysis tool. It produces results that can then be fed into an LCC program.
an architect or design engineer replacement. It does not check input, verify the acceptability or range of various parameters (expect for a limited number of very basic checks), or attempt to interpret the results. However, it does have several reporting features to help you do exactly that.