A logo has to be able to be reproduced in 2 colors. So far, this one can not. Not necessarily, but it's always good to have a 2-colour variant, as well as a black-and-white variant, along with the 4-colour. It's also good to have at least a plan for the 3-dimensional variant, especially with bigger companies that like to contract big shiny chrome or gold ones to stick on their walls.