Legacy, on the whole, feels like a port of a console game, not only with its emphasis on action but also with its simplistic view of space combat. While you can move up and down, most of the combat takes place on a fairly flat plane. Also cumbersome is the inability to save wherever you like, a doubly-annoying concern because the missions can take twenty minutes or more to complete... or fail. Blow it, and you have to replay the whole glacially-paced affair from the start.
The game is rescued, somewhat, by its multiplayer modes, which enables two-to-four-player deathmatch and co-op "survival" versus endless enemies via the internet. The shoot-everything-that-moves philosophy works a lot better outside of the campaign, when you're simply trying to blow human-controlled ships to atoms.
Legacy was widely foreseen to be the be-all and end-all of Star Trek games, and, in reality, it's just not. While it's nice to hear the voices of the various captains (especially Shatner and Stewart), it never feels like a Trek adventure. As an action game, it suffers from poor controls and awful fleet (read: wingman) commands that gum up the works. Still, wearing down the shields of those dastardly Romulan vessels and finishing them off with photon torpedoes can be satisfying, sometimes elevating Legacy ever-so-briefly above mediocrity.