Gosh, I am going to give fashion advice. I like the top half. Though I think you might be best off with pants that taper towards the bottom, or a snugger fit of pants. Those pants are a bit rectangular, and as you are tall and thin, some clothes, if they don't give shape, can kind of highlight rather than flatter that.
Ah sod it, I don't know what I'm talking about. Women are way better at this stuff. Bloody clothes.
Personally I don't think the skirt is really flattering. By the fact that the outfit would've been better with a black skinny jeans instead of the skirt means it has to do with shape. Maxi skirts are extremely hard to combine. I also have one but I never wear it since it's just too much work to combine.