they are ok,
you used to much filters also the second one is the best.
also in the second one you cant see the text.

I don't like the last one, mostly because the 'color' text not fitting at all. I don't really know how to CnC GFX signatures.

The first one I see some neon holes in the guy's neck.
Probably from over doing an effect.

Try removing the text on all of them because text is a hard thing to work with and can ruin a whole signature.
Stick with the plain image for now.

So....I say 5/10.
Good work for the most part though.

Edit: Also, it would also look a little better with a small:
2px or 1px border around the signature

the first 2 are awesome!
9/10

I specially like the graphics.
9/10.
Put some more effects on
there.

First and second one are pretty cool.

Gorrilaz:
-
Text is horrible
Background could be more like the render, it's a complete different style
Weird smudging on the arm with the cigarette
Weird purple/pink neon on the neck
Centered focus

+
Colors
Fading neon outlines of the render

Second one:
-
Centered focus
Right area

+
Left area
Red/orange lighting/smudges over the render
General feeling
Colors
Style
Text placement

I really dig the second one, but I find it hard to believe you made them all.
The shift in quality is huge. First one is okay for a novice, second one is halfway to pro.
I wont talk about the third one because I think that one is horrid.

Go look up the "rules of thirds", it will tell you more about where to place your focus.
You should really improve that. Your smudging is decent, and so are your colors.
Keep on improving!