I don´t like the plastic body of the lens.
Me neither, same thing with the 100L - but was Canon seriously thinking about releasing a metal body, or are they set on releasing plastic lenses from now on?
I had the same thought when it was released, but after I had used it for a while I realized that it is a very solid body. High quality plastic does have some advantages also.
5DIII, 1DX, 7DII, 8-15/4L, 16-35 f4L IS, 24-70/2.8L II, 70-200/2.8L IS II, 200-400/4L IS 1.4x, Zeiss 15/2.8, 17/4L TS-E, 24/3.5L TS-E II, Zeiss 35/1.4, Zeiss Otus 55/1.4, Zeiss Otus 85/1.4, 100/2.8L IS Macro, Zeiss 135/2, 600/4L IS II