Absolutely love my jacket, wouldn't be without it, you can literally hear the cars slowing down for you. Have been told by a passenger in a car "Fu&%ing ace jacket mate" and caught up by a couple of cyclists who have commented how much I stand out.
The downsides: - very boil in the bag, and also its hard to judge when to wear it - night times/early morning itsobviously its great but when it gets to dusk it just turns into a dull grey jacket, to combine with the dull grey day. I generally commute early and come home mid afternoon and have found the jacket very very effective on the way in, but not so good on the way home.
Still wouldn't be without it tho, if that makes sense.
To buy - do
Halfords not do their own version of this now, Boardman I think? Half the price...