Go see his new show at MoMA. Here's Peter Schjeldahl:
Eliasson is entertaining, yet his central concern seems less a working of spectacular magic than an investigation of how spectacular magic works. He raises awareness of the neurological susceptibilities that condition all of what we see and may think we know. This can be humiliating, as it often is in encounters with the menacingly proportioned spaces, grim videos, and noise assaults of Bruce Nauman, the greatest of post-minimalist explorers, whose influence Eliasson is quick to acknowledge. But with Eliasson the experience of our perceptual frailties rewards simple, open-minded humility.
In addition to the Nauman/Duchamp influences, I also detect some thematic similarities between Eliasson and Cezanne. Both make art out of our epistemological frailties, forcing us to pay attention to the strange mechanics of our senses. (I think Eliasson does this most effectively in "I only see things when they move" and "360 room for all colours," which will teach you a lot about your photoreceptors.) What I wrote about Cezanne in my book is also, I think, true of Eliasson: "His art shows us what we cannot see, which is how we see."