Jas - it hurts, but the amazing thing is most people forget the pain afterwards!
I would say mine was like really bad period pain (like the worst ever....) coming and going in waves every few minutes. The constant back pain I had was actually the hardest bit.
If you prepare yourself for it, and know that your body is capable - as well as having the support you need, you have the best chance of getting through it all safely and happily.