I am still messing around with Runescape (I wonder what I can use to record my bumbling around so I can post it online later). The game that I am going to talk about is Assassin's Creed on the Xbox.
Game Navigation: Basic game navigation was easy! I was able to get up and running without any issues. Some more "advanced" movements (like blending into a crown) I learned through on-screen prompts. But basic movement was easy and it leveraged my own previous knowledge of 3D space games.
Game Play: Game play was pretty smooth! No glitches or issues
Graphics: LOVED the graphics. Granted the original AC now seems like an antiquated game by comparison, however when I first got it, I was like a tourist! Sure, I did the missions, but I walked around like a star struck tourist looking at all the buildings, the surroundings and the people. This leads me to...
Degree of Immersion: Assassin's creed was totally immersive. This may also have to do with it being my first xbox game, so everything was new to me then, but I really felt as part of Al-taïr's world. At the end of each AC I couldn't wait for the next one! (Next one comes out in October, woohoo!)
CYTIE index: Pretty high! On weekends (when I usually play) I generally stayed up to 2 or 3 in the morning playing this game; and even though I did not want to go to bed, I did so anyway (so I wouldn't be a zombie next day)
Complexity: The complexity was rather low in that it had clearly defined rules that blended nicely with the story of the game.
Added benefit in subsequent games: tie-in to historical facts and artefacts!