i thought those big puffy jackets looked ridiculous on people wearing them around the city so i never considered getting one... especially when they were the trend back in college. but i started rock climbing since then and spending a lot more time in colder weather, and finally on a 45F day in red rocks nevada, i borrowed my friend's north face down jacket and was convinced of how awesome real down (vs synthetic) is. it's really warm and can pack into a small volume to save space in your backpack. the only downside is durability. the outer layer of a lot of down jackets can get torn or snagged easily, allowing the feathers to escape. and down doesn't like getting wet, so you can't wear it if rain is in the forecast. my friend describes it aptly: "it's like wearing a hug."
REI has a jacket with its own label that's less expensive than a North Face of Mountain Hardware model. The REI one isn't as warm or as packable but it also costs half that of other brands and gets the job done.