I love Crysis's art. It is a great, aesthetic, presentation of reality. The lighting is inspired and they did a really good job of selling the moods. I mean, if you pay attention you can see how thoughtful and deliberate it is. It goes further most other games I can think of at selling a mood with realistic lighting, and having it sort of sync with the levels dynamically.
The lighting transitions in the assault level and the first level are fantastically done.
The locale itself is gorgeous, and the alien designs are some of the most unique I've seen.
Honestly, I think when people complain about realistic games being artistically bland have this weird conception that the more abstract something is, the more artistic it is. But there have been entire movements in art about making something as true to nature as possible. To render it with an attention to detail and color, to create something dramatic and true. Crysis's graphics are one of the best attempts at something like that in gaming, especially considering how dynamic it is. The story itself isn't artistically significant at all, but the graphics are anything but bland.