Problems: The reliance of a photoshop filter is beginner level/amateur at best. No attempt to blend the big black box on the tshirt. Awkward cropping. Your name is bigger than the bands. Lastly, this isn't a poster, it's a web-banner.
since you asked....the only real problem i have with this poster is the dwarf arm on top. also, i hate posterized images that uses photoshops posterize function for no apparent reason. other than that, seems reasonable.