Good job my friend, I especially like the background, the font could be a little better on some of them. My favorite one is the Dwyane Wade sig, it's pretty cool. I also wish the sigs where a little bigger though.
Your style is ok to say the least, but a suggestion is that you put some borders to ur sigs maybe? Nice artists to be potrayed in your work though especially Mos Def, I love that guy. Though practice makes excellence Deve, so keep at it! Try using more brushes to make the sigs appeal more to the eye though, they could help in ur future sig making.
The style is popular mostly around more serious graphics forums...its a kind of trying to look professional and sleek rather than throw a bunch of stuff on it. Its more artsy and attention is placed on the focus of the sig, being the person in most of Deve's sigs, rather than just making a shiney eye candy sig. It takes more work than one would expect...but yea keep refining your skills