Jedi Knight only takes three short levels before you get the lightsaber. By contrast, its sequel, Jedi Outcast, had you wait six levels before you get your lightsaber and Force Powers. And the first person shooting elements in Outcast were far more flawed. The arsenal in Jedi Knight works to its advantage, despite the inaccuracy of the stormtrooper rifle, and are more effective than Outcast's arsenal.
More than ten years ago, when I replayed Jedi Knight after playing Outcast, I did originally feel that JK didn't flow as well as Outcast, and took me awhile to get back into the groove. However, Jedi Knight still had things which I found missing from Outcast, and much of its design choices deserve more credit than modern players have given it.
You guys may not remember it, but the level design of Jedi Knight was originally praised for being more realistic than most level designs at the time. It wasn't until Half-Life came out that Jedi Knight was considered the top of level design. Sure, the design can be confusing in places, especially with the secrets, but Jedi Knight was one of those games which influenced the way level design was done in later games. Take the Baron's Head level, for instance. That level made me feel like I was in a living community, gave me the choice to save civilians or kill every last one of them. The original Dark Forces couldn't pull that off, even though its level design was also rather good in its own right (despite its lack of save game).
On the point of the lighstaber, you give it too little credit. The creators had to bust their balls to get the lighstaber to have more functions than the typical melee weapons on the time. The axe in Quake is an example: all it could do is hack in one direction, and nothing else. JK's lightsaber swung in all different directions, depending on which direction you were moving while you swung, and could block laser blasts when you stand in a certain position. No other game pushed a melee weapon to be used the way a martial arts swordmaster would use it. It got LucasArts to try to push the lightsaber's function in subsequent Star Wars games: imperfectly at first with The Phantom Menace and Obi-Wan, and then significantly improved in Jedi Outcast and Academy. To this day, I'm still impressed with the way the saber functions in the game, and how it is still very effective if used right.
Though I love the saber combat in Outcast and Academy, I always got irritated with the limits of the saber styles, because I couldn't control my swings the way I wanted to, and it often left me wide open to being hurt. Even though JK's combat didn't flow the same way, I felt a little more in control of my swings. Plus, the Force Pull power felt more controlled than that in Outcast.
Which brings me to the Dark Jedi. Unlike the Reborn or Ragnos Cultists, the Dark Jedi didn't look alike, and didn't all have red lightsabers. They were all unique in their own way: it shape, size, force power, animation, and lighstaber. Maw was a muscular torso that could levitate and throw objects at you; Sariss could force pull all your other weapons; burn you with her eyes, and fought like a disciplined samurai; Yun fought like a cocky little jerk; Boc fought like a random maniac with two lightsabers; and so on.
For me, Jedi Knight was to Dark Forces what Half-Life 2 was to Half-Life. It brought the game's world to a level that felt more cinematic than the first, and offered new gameplay options that no one thought possible at the time.
As for the graphics, I like the polygonal graphics from that era. It's Quake-like, and is sort of like a modern art sculpture interpretation of Star Wars characters.