I agree with what the other guys said, The BG doesn't fit, but the work around the render is very good indeed. Change the background and add more of the purple and you'll have a very nice sig.
It's kinda hard to work on a canvas that small, so it'd probably help if you increased the size. The background color isn't properly blended with the render's color, and it's overall a little too dark on the sides. I like the fractal, though.
I'd say to improve the quality and blending of the background is to get a 100px soft brush, choose a colour which correlates with the render or the fractal, and simply brush over the top left and bottom right of the background. Set the layer to a mode which fits the best but I'd recommend overlay and tone the opacity down to your preference. However, you could also just get the burn tool and do exactly the same in areas which seems to bright. Of course theirs always an easy way out and you could just change the background I really think a space stock would fit well with the render due to the vibrant colours. Sorry for rambling on I get a bit carried away sometimes ...