I have to agree with Zephos. I don't pay much attention to the EU.
However, I would totally consider a game like Jedi Knight 2 part of the canon universe.
Spoiler alert.
- The game's story is incredibly consistent with Luke's character from ROTJ. He truly feels like a Jedi (calm, patient,and wise)
- Kyle Katarn truly feels like a Star Wars character. He is one hell of a badass but has his moments of vulnerability as well.
- Revisiting some of the most memorable places in the Original trilogy and the easter eggs are just plain awesome. There are tons of memorable moments.
- I like how Katarn tries to persuade Desaan to come back to the light instead of relying on violence (which is what a Jedi is supposed to do).
- However, I didn't like how the the villains obtained the power of the force. It felt more like a plot device to fight ghuys with lightsabers.
Overall, I feel the game was very faithfull to the original trilogy.