I'm normally a stingy one when it comes to signatures, considering how much space they take up; yours is sort of visually unsettling because of the height:width ratio. A good rule of thumb that I've at least followed is to keep the ratio around 1:4/h:w. You need to remember that there's a lot of other people that will inevitably post, and a very tall signature just makes more scrolling room.
As Psycho said before me, though, it's also really dark, despite the fact that I'm able to make out the subject matter after some thinking. It's also fairly clear that it is made of three separate images stitched together, something you might want to avoid; the transition between the middle image and the right image is very harsh and sudden, and visually frustrating!
Psycho covered ragdolls and GMod lighting well; you really have to play around with it to get the desired effect.
Overall, since it's nice to be picky about some things; I'd recommend retaking the three screenshots, smoothing out the transitions (preferably give them varying backgrounds of similar colors, [or a single black background and only take one screenshot] for a much more slick looking transition), and spreading the image out to be quite a bit wider.