Front indeed is really nicely done, but back needs rework. Try add up a few hangars... why not some sort of landing pad "moor area" over the engine block?
Also, think about various decorative elements such as antennaes, obseration tower, sensors, etc.
Just no one is going to rp a city ship... like if there were so many civilians on it to make up a city what crazy man would bring it into battle? lol
The Legion of Armageddon's first attempt at a RP revolved around a city ship converted from a Osiris Battlecruiser. There is RP available for City ships.
Its looking better, but you need to work on your texture mapping. Unfortunately it looks like you're just applying and tiling without any actual mapping.