I didn't co-sleep for an extended period, but from birth I did with dd2 and I got a hell of a lot more sleep than I did with dd1 trying to get her to sleep in a moses basket. I only started feeling tired with dd2 when I decided she would go in her cot, which rather serves me right I know. I just didn't want co-sleeping to become a bigger habit for dd2 than I could easily stop.
I would definately recommend it from birth, especially if you can get the hang of lying down feeding, dd2 would just kind of latch on then roll off when done, if I woke I'd turn us both over and start again, I'd be asleep before her every time.