I think the ship looks pretty cool, but to give some criticism I believe it would look better if the dorsal turret was altered a bit. Make the barrel shorter, and perhaps even change the shape of the turret. A round turret with a short barrel like the Babylon 5 Hyperion's Medium Pulse Cannons might be an idea. Or maybe just make the turret such that there's little clearance between the turret and the deck, so it's more like the Orion's turrets (but with a better looking shape). Also I'm not too keen on the two red lights on her either. I'd keep the turrets free of windows, and lights or whatever else because it's not Ten Forward, it's a big gun. So people shouldn't need to look outside anyway and lights just lets the enemy know where to shoot.
Other than, I think it looks pretty good (depending upon what scale it is to other ships). It's a damn sight better than I could do anyway.
I'm not sure if the E-Mortar is a new weapon, but the Leviathan and Fenris mount "Fusion Mortars" just FYI.
As an addendum, it might also be suitable to call the ship the GTF Nilus, where F means Frigate. Rather than E for Escort. The Leviathan was designed to be an escort for example, but its still a Cruiser. It could also give some continuity with other mods such as Warzone where they have the GTE Nidar for Exploration; but at the same time it might conflict with the NTF Iceni which is supposed to be a "Command Frigate" (even though F stands for "Front" in its name). Just a suggestion in any case. Volition might have called it a Battleship for all we know to follow their rather backward naming conventions (but naming conventions change with time so that's something I'm not worried about. In the age of Sail the Frigate was the strongest ship class in the navy, now its little more than an escort).
