I was immersed half the time while the other half I got a bit annoyed at bits. Like, I actually pulled over the first time I saw the edge of the map and the huge flatness to it in contrast to the the rest of the game. Or that one waterfall next to the gun shop. Other times I got annoyed with how the world was laid out. I hated how shortcuts were so rare and how every drivable path is in some area bordered off by large hills you can't even run over. The reason the respawning AI got annoying was because there wasn't a way to avoid them; it really should have had the simple violent path through the checkpoints, then the scenic route or something. Well, that and how goddamn perceptive the AI is.
I have my complaints with the game, less than a lot of games, most overshadowed by the positives too numerous to list. I thought Left 4 Dead was the best shooter of 2008 until I played Far Cry 2, now I can't really choose.
And the game is an amazing looking game. How the hell Gears 2 swept graphics awards, I have no idea. Shooting a rocket on the ground and watching it twirl around is so awesome.