Firstly, the quality of the jacket seems to be very good and the colour is very bright, fluorescent orange (which is a plus point for me as i like to be visible at night), much brighter than it seems in the pictures.
The fit is fine. I am 6,1, 84 kg and a medium is fine for me with room for clothes underneath.
The problem is is that there is no ventilation in the jacket whatsoever and the material is not breathable despite what the marketing material might say. Consequently if you happen to sweat whilst running,the sweat builds up inside the jacket. I have taken it out on one run, where it was cold outside, and ended up soaked from my sweat as it wasn't allowed to escape into the atmosphere.
I will definitely keep it for very rainy runs, but wont be regularly wearing it when it's not raining (espeically not if it is warm outside). In the mean time, i might just have to get a hi-viz bib.