In reply to matejn:
My jacket has just arrived and I have to say, from poncing around in the house, that I am very pleased with it. The jacket covers my bum. Even while sat down or flailing my arms around, the jacket does not rise above my bum.
When I buy stuff like jackets, fleeces or tee-shirts I normally choose a large size, however the medium fits me perfect with a thick fleece under it. Its snug but not constricting. I was worried about comments regarding arm length and I'm happy to report that the arms are the perfect length, neither rising up my arms or below my wrists while throwing my arms around.
And a huge improvement over the Prism jacket are the extra pockets, including an internal pocket for small items such as a phone or wallet.
The attention to detail is especially welcome around the zips and draw strings. The zips have snazzy simple designs that work well with gloves and the hood drawstrings have a great way of being stowed so they don't smash you in the face by flapping about.
But most important of all, the jacket is considerably warmer than the Prism, which itself was a toasty garment to begin with. Got to say, I much prefer the flux but both garments are superb.