The Enterprise was the first Earth-built starship to mount a warp drive capable of achieving Warp 5 (125c), although even that was mostly a theoretical limit. In 2154, it had a maximum rated speed of Warp 5.2 (140.6c).
When the ship left port, it was armed only with torpedoes of unspecified yield (possibly comparable to merculite rockets) and low-power pulse weapons of unspecified type; both proved to be rather feeble compared to the weapons carried by the ships of other space-faring races at the time. The crew were able to install three phase cannons without returning to Earth for a refit, substantially improving the ship's combat capability. The ship's original torpedoes were eventually replaced with photonic torpedoes during a refit at Earth.
The NX-01 used polarized hull plating for defense (a ceramic which became harder when electrical current was passed through it). Like the ship's weapons, the primary defense proved quite weak compared to the shielding of its contemporaries.
The Enterprise was the first Earth ship to mount a transporter system, but the device was not generally trusted and only used to transport living people as a last resort.
Notable Crew Members
Complete Lack of Lineage to Other Trek Ships
Despite there being on-screen evidence for spherical type starships shown throughout the earlier Trek shows, NX-01 looks like an Akira-class starship, albeit made a bit less fancy.
- ENT "Affliction"