Oh, didn't see this last time through the art board.
1. Looks great. Text is a tad distracting but not enough to make it terrible. Maybe a couple subtle effects would help, but I see what you were going for.
2. I really like how this one came out. The red and bluish lines are a nice touch. Mind posting the render for this one? :3
3. You did a great job at depth. I'm not so much a fan of the colors. Seems like you could have blended it all together a bit better.
4. Seems alright. The lighting could be worked on a bit. Flow and depth are okay. [ran out of time I have to go]