If you want to command a complex starship in the world of Star Trek, there is no better game on the market.
Environment:
The Open-Maps are unique and the systems are infinite in size. If you want to pick the second star to the right and fly on through morning you can. Where the systems are not 'life-like' in size, they do allow you to travel from planet to planet, exploring places like gas giants (where you can fly through them), planetary rings (good for hiding or running), black holes (disable your enemy and watch them slowly get sucked in), nebulas, planets, or stars. The environment is completely 3-D, so you can fly/fight in any of the 6 directions.
Controls:
To start with you can control you entire ship, from the six shield and weapon arcs, to your internal security systems. For the most part you control everything through a series of menus accessed by numbers on your keyboard. They take a significant amount of time to get good with, but there are many ways to setup "power allocations" that allow for fast transfer of power to key systems depending on the situation. Beyond the menu system you can also enter each station and control them directly. Most commonly used will be your engineering and damage control stations, where you will setup power allocations and concentrate repairs. Otherwise the game plays like a slow dogfight, with your ship responding like a 'real' starship, slowly. Skill comes with power allocations and maneuvering to allow you to keep the enemy on their weakest side while you keep up your strongest side.
Combat:
As mentioned above you have six shield arcs and six weapon arcs (although most ships only use 4 of those arcs for weapons). Damage taken affects systems in those areas of the ship... aka if you take a hit in the engines, your engines will produce less power and your speed will be limited. Repairs are a constant fact of combat and can be increased in effectiveness by allocating repair teams more power. In cases where your ship has taken significant damage to particular areas, you will loose the ability to completely repair certain systems... at times you may not be able to repair them at all. Placing more power into your shields or weapons will assist with your combat... while having marines and security systems in place allow you to repel boarding parties. You have complete control on your ship, so at times you may completely shut down non-essential systems for others that are more pressing. I found fun in "toying" with enemy ships, tractor beams, boarding parties, all are great fun.
Single-Player:
For its time (and even now) the storyline cut scenes are very good and make for a very fun single player which will take you some time to complete. One negative is some missions take some time to figure out, meaning you may be forced to re-start several times for several missions.
System Requirements:
For their time the graphics were incredible. By todays standards they are still pretty good, but nothing To be amazed over... One of the largest problems is that as you increase your resolution your UI can become screwed up. Also, Klingon Academy has glitches and problems with XP and does not run at all on Vista so for many of Today's players, the game is obsolete. It is also advisable that you have a joystick for controlling your ship as that will work much better then mouse or keyboard.
Wrap Up:
Personally I found this to be one of the best games I have ever played. Despite what my below comments seem to say, I have given this game a 9.0 score and still have one of my old computers around specifically to play this game.
The Good:
High Complexity, Deep Storyline, Immense Space, Real Space Ship Control Feel (it isn't a fighter), Excellent Star Trek Lore Built Into the Game.
The Bad:
High Learning Curve, Bad Compatibility with Newer Operating Systems, High Complexity Can Make Play Very Difficult (personally I have found that running with a co-pilot controlling your systems / keyboard works very well).