Please give me comments and critique...... the render waz taken from planetrenders.net..... i hope thiz iz ok

The render (like many from planetrenders.net) requires attention. The extraction leaves much to be desired. As for your additional elements, the image works in terms of palette however the choice of brushes (specifically stock photoshop maple) leave a lot to be desired. Try to avoid using the standard stock brushes as they're painfully easy to recognise to anyone who's used photoshop and tend to distract as a result.

Nice Idea ;D

These are the things that I think you should do:
1. Extraction. I don't know you extracted or vectored the character, so I'm assuming that you extracted the character. Take a look at her face, I think you may want to clean some of the parts, especially near the eyes and chin.
2. Hair color. I think almost all parts are too saturated, all except the ones near his neck.
3. Lightning. It kinda needs some work, but personally, I do think it will be better if you remove the lightning.
4. Background. Actually this may become a nice abstract wallpaper. However, I think you should remove the leaves brushes and blood brushes that are too roundish. I'm suggesting to look at DeviantArt to look for some nice blood splatters brushes. And about the arrangement, I think you should try experimenting until you find a nice composition. Do you know that textures actually make wallpaper much much better? They do. DeviantArt has a lot of nice textures, but I recommend you to take a look at DA! Desktop Anime. Because the textures are really nice. I usually change the texture layer blending mode to "soft light", but you have to try other blending modes to see how they look.

If you have some parts that you don't understand, feel free to ask. ;D
If you use Photoshop, I may even describe the steps.
Well, I hope my comment can help you.

-tida