It is very common to your other tags, Try experimenting with different styles until you find one that you are happy with :y:
Here's your cons of this one mate. Remember this is just constructive criticism:
1: I feel like the render is too centered. Not always a bad thing but You have added literally no depth what so ever to him, I think you need to work on that more :y:
2: Yes, as the others have said it is mono-tone. Basically monotone is when the signature is simply whored with the same colours or blue for example. try using colours that compliment blue, Such as pink perhaps

3: I like the flow of the sig, You seem to be showing an improvement with that however the small c4d used to the right and left of his head disturbs that flow and to be frank, doesn't really look good in my opinion.
4: Lastly, I think you should add a light source, it adds depth and makes the tag look more realistic, but then remember to make the lighting correct, do that via the dodge and burn tool, or simply go to filter>render>lighting effects. And play around with that
Keep up the enthusiasm and keep reading tutorials. Deviantarts would be the best place for that :y: