Damian is right, if you did sharpen it, you sharpened it too much indeed. And this why it looks pixelish. (ie. you see the pixels or "boxes" how Damian called them).
And that's not good. At first I thought that maybe this is a result of you uploading it somewhere - but you clearly sharpened it too much then. You got to be careful with that, it's easy to overuse it. xD
The text itself is good but I just can't bring myself to like that sort of violet color glow on it. You should of changed the color to something else and lowered the opacity some. Because I don't feel like the violet color fits to the rest of your signature.