The sketches are actually quite good. Just listen to the fellows below. Basically the sketchy aspect is the downfall for me. Giving varying line weights to your design will give it more depth. The writing itself is cool but could be unnecessary if you deliver the focal point itself better.

I think this design would benefit heaps from some bolder lines, especially the outlines. Also, I have no idea what that text says – imo it should be discernible in the large preview, because that’s how people will view the real shirt.