It's designed for biking, so the back flap extends down over your butt when you're in the saddle. And they're Scottish, so they know rain.
Tried on a size M and it fit me well, but they only had it in the gunmetal grey. It's slim-fitting enough to run comfortably in, but if I'm biking/running in the rain I'm going for the one in "don't-hit-me-you-fucking-oblivious-driver-yellow" rather than the one named "Stealth".