Yes, story is great and treating and existing property like Star Trek properly is important, but none of that matters if the game isn't fun as well. The combat in STO isn't wholly original, but it has enough fun aspects to make the game enjoyable, for the most part.
Space combat is truly the highlight of the game. Battles are a constant strategic fight for positioning, keeping your strongest shields toward your adversary while simultaneously aiming your weapons at his weakest is an enjoyable challenge in most cases (fans of the Star Fleet Command series or Star Trek: Legacy will feel right at home here). Ships are upgradable with different categories of loot (weapons, science consoles, engines, shields, etc...), giving the game that addictive, constantly searching for upgrades quality that keeps people coming back to games like Borderlands and WoW.
Working your way through the various ship classes is also an excellent motivation to keep leveling. Every 10 levels, players get access to a whole new tier of ships, and have their choice between three types (Science, Escort, and Cruiser), each with a unique combat role to fulfill. Some ships are instantly recognizable (Galaxy-Class Cruisers, for example), while others are new designs created specifically for the game.
Page two has more, including ground combat, instancing, and our final verdict on the game.