I'm not sure what the other reply said, though I guess it was either ass-esque or a one-liner, since it has since been deleted, so I'll say something productive.
The spikes look like spikes, but they look like something done in a couple minutes, lack contrast, and don't really say "Hey, I'm a sharp spike; don't land on me!" to me. Perhaps they'd be better in context, but standalone they don't really appeal to me.
I have no idea what that second thing is, so I won't even try to critique it other than to say that it could probably use more contrast, whatever it is.
The shirt looks like a shirt, though it would probably be a good idea to clean up the lines (remove "jaggies" and double-pixels) before trying to color it.
The stereo cords are the best of these by far. I could immediately tell what they were, they aren't lacking contrast, and they show a good sense of how light reflects off things. However, there are still a couple things that probably want tweaking. Specifically, the red cord suffers harshly from banding. Banding is when the bands of color all line up and emphasize the jaggedness of the pixel medium. Here's an edit to show how to take care of it:
Note that that was a very quick edit and I'm sure it could be cleaned up better, but you get the idea. The same concept probably wants to be applied to the spring-looking area, since it also suffers from banding. Also, I'm not quite sure where your lightsource is in this one. The lighting of the metal implies that light is coming from the top of the image, but the cord is pillow-shaded, with light coming from the viewer. If light is indeed coming from the top, the shading of the cord needs to be revised.