Ah, Jedi Knight. Allow me, if you will, to babble on this subject.
For my money, Dark Forces II: Jedi Knight was the best of the entire "Jedi Knight" series of first-person computer games. For that matter, judged against the state of the art at the time of its release, it's one of the best FPS games I've ever played.
The original Star Wars: Dark Forces (DF) was a very good game. For starters, it was a first-person game set in the Star Wars universe. That went a looooong way. TIE Fighter and X-Wing were also first-person games, but they were flight sims; they didn't give you the same feeling of immediacy as a ground-based game with textures you could see and objects you could interact with. I remember when the demo for DF was released -- we could not wait to play this game. It looked and sounded like Star Wars!
In terms of its gameplay, DF offered large vistas, giving a much greater feeling of openness than Doom, its closest competitor and obvious inspiration. DF also required the player to solve puzzles that were more difficult than Doom's. Finally, DF gave the player the chance to play in the Star Wars universe, which was a real hoot. Sounds, artwork, weapons and enemies all contributed to giving DF a distinctive feel and effectively communicating the Star Wars vibe.
That said, Dark Forces was flawed in some ways. Although the level design was generally good, there weren't many different types of opponents. I also felt that the end-game boss fight was a bit anticlimactic. But DF's worst offense by far was the decision not to allow players to save their game except between levels. The developers obviously believed that saving and reloading the game made it too easy, and so simply left that feature out. That wasn't fun. (Surprisingly, some developers still haven't learned that this is unacceptable. Although you could get around it with a console hack, Far Cry was designed not to give players a save/reload feature.)
Unlike some sequels, Dark Forces II: Jedi Knight (JK) took everything that DF did well and improved on it, while adding new features to make the game even more fun. Levels became still more wide-open, to the point that I found myself hugging exterior walls in some places, nervous about moving. The number of video resolutions at which the game could be run were increased, so that the graphics appeared much sharper than its predecessor's. JK looks a little cartoonish now, but it was reasonably good for its time.
Importantly, the level design for JK absolutely rocked. Not only did every single level do an excellent job of reimagining Star Wars locations and challenges, they were brilliantly imaginative, and they looked and sounded and played great. Among the many memorable levels was one in which the player has only a few minutes (real-time!) to escape from a damaged spaceship which is falling to the ground. As the bulkheads groan and klaxons blare in your ear, and the deck heaves and pitches at crazy angles, you're forced to scramble frantically from one part of the doomed ship to another in search of a way out. It is incredibly frustrating... but incredibly immersive. (And incredibly satisfying when finally completed.)
Another very nice touch in Jedi Knight is the addition of the lightsaber as a weapon. Being able to take on opponents with the lightsaber was something DF didn't offer. To showcase this feature, JK even included several lightsaber fights with bosses of increasing difficulty. (It's pretty remarkable, but I swear that the leaping, whirling lightsaber moves used by Yoda in his fight with Count Dooku in Episode II looked amazingly similar to those used by one of the enemies in one of the lightsaber fights in JK.)
Best of all, JK pulled you even further into the Star Wars universe by the introduction of Force powers. Although we take them for granted now in Star Wars games, abilities like Force Jump and Force Choke appeared first in DF2: Jedi Knight, and were incredibly fun to use. One interesting aspect here was the way Force powers were improved. When you finished a level, you were given "Force Stars" which you could then spend on learning new powers or improving existing powers. Where this got interesting was that you earned more stars the fewer times you saved and reloaded during a level. Apparently the designers were still fixated on the idea that letting players save and reload was undesirable, but at least with JK they figured out a way to reward players for not reloading, rather than simply denying them the ability to do so at all as they had in DF.
And just to showcase the quality of this game's engine, the Mysteries of the Sith expansion for JK (which featured Mara Jade) even included a deathmatch level that mimics the interior of Cloud City in The Empire Strikes Back where Luke and Vader fight. If you break open the large circular window, you get sucked out and must try to land on the narrow ledge below. You can even damage the railing with your lightsaber just like Vader did after Luke injures Vader in his shoulder.
The only questionable aspect of Jedi Knight is the use of full-motion video for its cutscenes. This was the Big Thing of the day before developers realized that it actually hurt the game if the acting wasn't good -- which it usually wasn't. Unfortunately, with a few exceptions, the acting in the FMV scenes of JK... wasn't good. (An exception to this was Angela Harry as Jan Ors. Her naturalness improved every scene she was in.)
Overall, I have to say DF2:JK was by far the best of the series. JK2: Jedi Outcast wasn't bad, but it didn't push the gameplay envelope nearly as much as JK did, and its levels weren't as imaginative. As for Jedi Academy (JA)... sigh. I didn't enjoy it at all. By comparison with the earlier Star Wars FPS games, the levels in JA felt unimaginative and cramped in both area and duration; the story was weak; the Force and lightsaber gameplay was "been there, done that." In short, Jedi Academy felt like a console game. It actually wasn't all that awful -- it just wasn't a good PC game, and it suffered by comparison to the previous Star Wars FPS games.
On the other hand, it makes DF2:JK look that much better. Wow, but that game was good.
Even with the full-motion video cutscenes. :)