I took Ambien for about four years. I wouldn't say that I was addicted as I stopped voluntarily and I never abused it (i.e. taking any recreationally, or combining with other drugs, etc.), but you definitely grow dependent upon it. Unless I was flat out exhausted falling asleep without it became more difficult and I found I couldn't sleep more than four hours in a night without it. What I tended to do was fall asleep without it if possible, and then when I woke up typically after four hours, I'd take one and that would get me four more hours of sleep, with no lingering effects.
I never had any of the freaky stories others have related, but my girlfriend has borrowed mine and it knocks her ### out, and she's groggy all the next day too. I can definitely see where it would mess you up if you're mixing it with stuff. On those occasions when I'd take one before bed and I'd stay up until I felt the effects, even walking to the bedroom could be a challenge. The thought of me alone in the apartment or with my young son in a fire right after I'd taken one of those was always unsettling.