1. giantkillerjay - What I like about this image is the simplicity of it. It works in context of illustration, although not necessarily CG-heavy or have the appearance of an emphasis on that style. It is also hard to tell whether the creature is a plant or closer to a mollusk, due to lack of greens while still having eyes. Nevertheless, the charm is in the storytelling. It is unusual to see a cross-section of something I would expect in an architectural diagram (where I've worked for couple of years).
2. SteFlack - The colors and ambiance set the emotional mood of this piece. The neck area of the girl is a bit hard to see--the plant may be choking her. On the surface, though, one might not necessarily read this piece that the girl is in trouble (if she is). In fact, she could be a dryad and the flowers may be growing out of her. The backgrounds are particularly fascinating to look at.
3. DoctorDark - I liked the use of purple and yellows. There's drama. Still, his left hand looks a bit odd. His expression is spot-on and I like how the image comes toward the viewer. Now, the monster may not be so easily read as a plant due to color. Admittedly the fact that the image is diagonal yet having the top part of the plant conveniently fit the space right above can make the image feel a little too contained--feel free to let the image be cut off by the edge of the picture if needed.