They're one of the few ships in sci-fi that are anywhere near inteligently designed. The launch tube system would probably be better off being replaced by a hanger (or just launching the Vipers out of the landing bays), but that's my only major complaint.
As for whether we could build a 1.2 kilometre long space-going warship with cannons and nuclear missiles, it'd cost far to much to be anywhere near realistic, and be far too difficult to build.
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