This is personal opinion only
As many of you know, I began taking (on a limited basis) a new pain medication called Nucynta, which was release in June 2009. Well, the jury is still out on it for a variety of reasons. 1) I started taking it after my epidural, so my pain level has not been as high as it was previously. 2) I have only been taking it at night and only when I need it for pain, as opposed to on a continuous basis.
Some concerns that I have had even with my limited use are it does not appear to completely stop the pain even though my pain levels are significantly lower because of the epidural. It reduces the pain, but does not eliminate all of it. Also, I have noticed a dramatic increase in visual migraines the day or two after taking it and a headache in the morning. Although the first time I took it I felt a little drowsy, I have not noticed any significant drowsiness since. I definitely will not fall asleep after taking it and most nights I end up all night long unable to fall asleep.
So, that is my initial impression of the drug, but I will have to take it much longer and probably at therapeutic levels to really evaluate it properly. I don't know if I will ever get to that level unless the epidurals stop working.
Everyone's body reacts differently to drugs, so other people's result may be dramatically different than mine. I saw one post where someone went directly from Percocets to Nucynta w/o any ill effects and no withdrawals. I would still like to find someone who has stopped taking Nucynta and see how their withdrawals were compared to other opiate based drugs.
So there is my unscientific, opinion of the drug.