The Earthling Cruiser is a vessel of happenstance. Humanity was brought into The First War with almost no preparation. It was only their long history of proliferation that allowed this vessel to be so effective in the (ultimately losing) battle against the Ur-Quan Hierarchy.
The Cruiser is a little below average in speed but has a respectable turn rate. This complements its weaponry well when facing off against opponents prefering a medium encounter range, notably by either closing that range or expanding it rather quickly.
The Cruiser's primary weapon earned them quick respect in the Alliance. It's not terribly advanced, but with the number that were stored in Earth's Peace Vaults during (and before and after) Humanity's wars against itself they were a pleasant surprise to their allies and a devastating blow to their enemies. The tracking Nuclear Missile is a simple concept. Put the biggest explosive that a post-industrial nuclear society has on the end of vaguely competent tracking and navigation system; repeat several million times. This weapon has long range and can correct for significant variation in original trajectory and later enemy movement. Unless the weapon can be shot down (no mean task) or cunningly evaded, the power of the atom will be unleashed on the enemy crew.
The Cruiser's alternate weapon is a very short range point-defense laser system, based on mid-1980s "Star Wars" missile defense technology. It fires lasers at enemy ships, projectiles, asteroids, or anything else that is close to the Earthling ship. This system is proof against daughter ships like the Ur-Quan Kzer-Za Dreadnought Fighter and Orz Nemesis Space Marine, as well as some weaker projectiles.
The Cruiser is highly effective when used as a stand-off ship; it is capable of delivering punishing blows from great distances, and the auto-tracking aspect of its weapons makes aiming of secondary importance. Its slow speed makes this easier said than done, however.