You are off to a much better start than I was when I first started using maxwell. The glasses like Thomas said need something. Try backlighting them like you did in the chair image to give the image more drama. Also maybe space the glasses out closer to the edge like the bed image. There is too much negative space on the sides, which does not help the shot.
Bed image is close, but judging from your floor shadows it looks like you have too many lights coming from a similar direction. Try to bring it down to two or three emitters that are whose position and intensity doesn't cause the busy shadows on the floor. This is distracting from your design.
Tableware image is a litte dark on my screen, and the last image could stand to be a little brighter also.
The material on the phone screen needs some work. It is too matte black. I would put an actual screnn mxi texture on it, or give it some reflection, and a little bit of roughness.
As for your designs in general me like

Industrial Designer
Concept Center International
www.ericlagman.com