Yes, the contractions were painful (but not horrible) and I absolutely had to be upright during them. They were pretty consistent, always between 7-10 minutes apart. There was never a break, so I got zero sleep for two nights in a row. They didn't do much to my cervix.
However, 'real' labor was a snap.. there was one contraction that was different than all the rest (not more painful, but all of a sudden it drove me nuts that people were talking during it), and the baby was in my arms in under an hour. It was intense, but the contractions weren't actually that much more painful that the prodromal ones.. which is why I hesitated to call the midwife and she missed the birth. So, in a way, I was grateful that I had such an easy birth from that perspective, but those 48 hours were so incredibly wearing. If it had been off and on and I could have gotten some rest, it would have been totally different.
I don't think she was malpositioned, though I did do some exercises in case that had been the problem. The change came right after I had told my midwife that I'd had it and if the baby wasn't born by that evening, I was going to the hospital. I was sitting and talking with my mom (who works at said hospital) about the specifics of transferring, and that's when I had the first 'real' contraction. So I don't know if there was some sort of subconscious/psychological aspect to it.
I'm just hoping that I'm not sleepless for several nights before giving birth, 'cause that truly sucked.