the glass (refraction shader?) seems to "lag behind". If you rotate the camera it looks like the glass (or more the room behind it) is moving/shaking a little... other than that, great work! The portals look too much like a door though, and too little like portals. Maybe a shader on them? Some distortion? some effect on the edge of the portal?
~"I never let school interfere with my education"~ -Mark Twain
