There is no such thing as the garbage patch[1]; any such pictures[2] you may have seen are of other areas that are certainly far more polluted (it doesn't change the tragedy of it or the disgusting nature of such things, but it does change the premise of the argument).
There is, however, a significant problem with regards to the micro-plastics and other such small particles floating about in great number. The problem is that no one knows how these are affecting the ecology of the oceans on a large scale[2].