I used to have a pierced lip and had to give it up after three years as it was rubbing my gumline and would have led to dental problems down the road. Placement and what type of jewelry you wear are really important if you want to avoid any dental snafus.
Other than that, it doesn't really feel any different than any other body piercing. Hurts to get pierced, sore a bit when healing, strange until you are used to it and then it just seems like it was always there after a while.