Either a white border or none at all would fit this signature much better than black IMHO. I really like the stock you used, nature stocks in a sig are, if done right, mostly in my favor. For me, that pink spot just above her right eye (from our view, not hers) is a bit distracting. Text is the one that needs the most improvement. Make it contrast more from the background
Border is very minor problem. Glad you like the snow castle stock. I didn't notice that pink spot till just now... As for the text, I suck at it, as usual. I don't really have a problem reading it... I don't see why it needs to contrast more, if it does it'll distract from the focal.
Wow, this sig is awesome! I really like the way you took an anime render and used a realistic background with it. The lighting is very nice, and the blending of the effects with the render is really well done. The color scheme is pretty good too. As RaBiiTTT said, a white border would be nice. The text placement is fine, and I don't think it should contrast any more than it already does, but you might want to try a more script-style, fanciful font to match the mood of the sig.
Its too washed out, theres no real variation in colour and perspective to make it interesting to look at. I'm not sure about the choice background as the colour scheme clashes with the render. I'd give this one a miss I'm afraid.