I had my bottle until i was 7. it was purely a comfort thing. I remember coming in from school and running to get my bottle. i still think of bottles quite fondly and sometimes i think of stealing my little girls one as it looks so comfy but i have been strong and not gone back to the bottle yet.... It did me absolutely no harm than i can see other than a ribbing now and then from my family about how old i was when i gave up. don't worry your little one will loose interest at some stage as long as they can take other drinks from a cup there is nothing to worry about.