Technically good, the first one looks cold and dead. Also, your books look like they have a library indexing sticker on them.

Might want to return them to the library before you rack up a large fine.
The third one, I don't understand what it is. A house? It just doesn't seem like useable architecture, maybe art?
Same with the third. Cold, dead, unappealing. I don't get it. What is it? And hire a landscape designer here, too! Technically, I have to question the sky background here too. The horizon in the scene and the perceived horizon in the photo don't seem to match.
All of your renderings are very technically great. The subject matter and scene composition just are lacking to me.
Brian Looney
Maxwell + RealFlow
http://www.turbosquid.com/Search/Artists/Bubbaloo
Help! I'm dispersing into a haze of probability!