I got onto it with my first labour, had just the TENS at home and headed into hospital then got onto the gas. It took me a while to get the hang of it though - for a while I I was pacing the room sucking the gas and then vomiting. But once the MW and DH coached me on how to use it, I found it invaluable.

Like some others - I found it just as useful for focus.

A key for me was to stop using it once the contraction had peaked and just take deep breaths of normal air. That helped clear my head in between ctxs.

I even took it into the shower - they had no gas point in there (major design flaw if you ask me!) and the hose wasn't long enough to reach, so DH decided to make an extension for me. He did a bit of a Macguyver - knocked it together so it reached the shower. Bless him!

Second time round, didn't need it!