For many the memory of a smell, invokes powerful memories, and for some can even transport them (almost) back-in time.
For me I have the fondest memories of stumbling upon CK one for the first time, i was about 18 yrs old, and is reminiscent of my old college days!
Onto the fragrance itself, CK ONE os extremley clean, lightly fruity, and subtle musky notes. What I like about this one, is its ablilty for you to make it your own. What I mean is all fragrances smell differently on different people, and CK one as a scent allows "you" to actually wear it and add it as a signature scent for any individual.

It may surprise some (new to the fragrance)
From when you put it on in the morning, for the first couple of hours you'll recieve these pleasant light, woody notes with citus undertones, that during the course of the day blend into a delicious musky almost creamy affair.
Lets make no mistake here, this is (one of ) the best sellings fragrances of the last 20 years, and for me it's not hard to see why!
Its reall success as far I see it, is its mass appeal.
Great fragrance!
Mark