I like the colors, but composition is meh. The joker's head is in the middle of the sig, which makes it look odd. If you moved it up more it would look better. Also around his head you can see that you oversharpened it by the low quality look.
I iz really diggin this sig... Great job on it! Also the color one is better. I like the lines and symmetry of it.
I don't think this pic really makes a great sig. You kinda need the whole image to really appreciate it. =/
The effects are real nice man. I would recommend adding some text and sizing the signature a bit down.