Really well done! Maybe some writing on the markerboard. Only other thing is maybe use some scanned in texture samples for the wood on the desk. A smaller grain pattern might look good as well as a few different texture maps of the same wood so they repetition isn't that obvious.

the light fixtures seem terribly flat. i agree with the texturing comments, i'd also suggest some slight variatons in the chairs, they seem too perfectly placed to be natural. the POV is excellent, and the feel of the room is also top notch.

This certainly has the look and feel of a class room setting, in a corporate bldg. In that context it's an exceptional image. I think its very well done.