My DM didn't tell me what the pain was like on purpose - she just said 'it can't be that bad otherwise no one would do it again'. She told me that she had deliberately not told me what it was like for her until after I had a sub-optimal labour that ended up in EMCS as she didn't want to scare me! I didn't find this helpful and would have rather been more prepared!
I had two 'back labours', and if anyone asked I would gladly try to describe as best as I could, so that they knew at least one of the ways it could feel, in a multitude of millions of feelings that I'm sure so many women feel during labour.
Personally I felt the absolute worst squeezing pushing sharp pressure on my lower back/spine each time I had a contraction. It was like someone was trying to stab me from the inside and the outside each time I had a contraction with a hot blunt object. A TENS machine was invaluable in my second labour, when I was anticipating this back pain. The hurt of the TENS on full, was better than the hurt of the contractions.
As far as the actual birth, no one told me either that if it is vaginal, you might actual feel babies head coming out and touching sensitive bits 'down there'. So it's such a strange sensation. The pain that you know will not stop until you get the baby out - which is the thing that kept me pushing!
I think I could describe my labours quite accurately, but I don't know if they would represent the birthing population! I would definitely use that as a disclaimer if I was talking to anyone about it!