There's no question that it's a habit with me, part of my daily ritual. I'm not sure whether or not I'm addicted to nicotine. There are days when I just can't smoke for one reason or other, and I don't seem to crave it or dwell on it during those times. I've not had to go without for more than a day, though.
Pipe smoking is certainly not a hobby to my way of thinking. I would consider related activities like pipe collecting, restoring, carving, etc. (none of which I do) as hobbies, but if smoking is all you do then I wouldn't call it a hobby. Kinda like calling drinking a hobby...