Overall it could use some more "details", look at the RM Cruiser for comparision and you will see - even without textures - the ship already looks like more than "a block".
My biggest concerns are the front and the mid section. Both lack those details and look too "flat" at the moment.
That RM cruiser isn't the vanilla/ingame model, has too many details for it to be.
I kinda like the flat middle section, actually. Makes me think of WWII German tanks like the KT and its frontal sloping.