It's totally your decision (in most circumstances) but you really don't have a clue what the pain is like until you're in the the thick of it ... and it's too late to back out!
I don't regret my tattoo and look fondly at it as it holds great memories (it's hidden from sight unlike my DC!
) so I have great hopes for my future feelings towards my children 
I'm being light-hearted here so it's not a 'real' comparison before anyone flames me!
It's just that I used to have the view that you shouldn't moan about children as you decided to have them ... until I became a mother of course! Now I know how damn hard it is!