The lighting was stunning, especially when you went for a swim - the rays of light and reflections from the water on the sea bed were breathtaking. Of course, lighting on its own is all well and good, but it's never going to deliver a truly immersive experience without some good shadows. It's lucky, then, that Crysis also delivers on that front too - the shadows are right up there with the lighting effects and really helped to make for an immersive experience.
Check it out at Bit Tech.