I was looking for a warm, lightweight jacket for work as I'm constantly outside in less than ideal conditions. Initially I was considering purchasing Columbia's Kaleidoslope Jacket, but decided on getting a waterproof jacket instead.
The Glacial Glide is made with heavier material than the Kaleidoslope, but it IS waterproof and also offers Columbia's Omni-Heat technology. I also think it looks pretty sharp for being a waterproof jacket.
All that to say, this jacket will hold in heat, but you still will need to layer up if you're constantly outside in weather below 30 degrees.
For sizing purposes, I'm 5'6"/130 lbs and the small fits me very well, with a little bit of room for layers.
Also -- I got this jacket for $135 via Backcountry on Amazon, as opposed to $180 in stores. Great deal, great jacket!