After a motorcycle accident where I shattered my collar bone and split my shoulder blad in 2 I was given Demerol, all I did was sleep, wake up & eat, then back to sleep. I did not like it at all, but then again I was in the early stages of my alcoholism then and all that sleeping messed with my drinking!!! Now in the later stages of my alcoholism I really can't say, I may have liked it! As already said, take it as prescribed and you will do fine.
If you find your self trying to convince your self that a few more then prescribed is a good idea it may be wise to give the script to a freind who will keep you to taking them as directed.
Demerol for me was sleepy time, morphine was lala land, I was given that by the ambulance crew...... if that was easily available I may have gotten into trouble with it.