Size is relative.
This is going to be a fully outfitted Role-playing ship, being built at a 1:1 scale, so while at about 450m long it might seem big, once you include quarters and other facilities to support a crew of hundreds, plus a good size cargo bay, additional bays for a smallish compliment of shuttles and a few fighters, as well as water, atmosphere, and fuel tanks, plus weapons systems, shield and engine blocks along with power blocks to run it all, and system control rooms to allow the crew to 'manage' all of these systems... it'll fill out. Probably.
For comparison I've already built a
Corvette that measures about 220m (I'm probably going to redesign that one at some point though), and I'm planing to build a Destroyer that will come out somewhere between 350-400m, and then a
Light Cruiser that will be around 500-550m. A Dreadnought would measure about 2000m, but I'm not sure if I'll ever get around to building one of those.