I LOVED using gas, it was great. Biting down on the mouthpiece was as important as what was coming out of the end of it for me.

DS1 - I used it and it was brilliant. When it was time to push the midwife said “no more gas”. I protested and though I had “won” because I kept on using it. Much later DH told me that when she said that she turned it off at the wall so I was just breathing air.
DD - I sucked too hard and fast and completely knocked myself out. They wouldn’t let me have it at all again after that. My experience was still great though and being knocked out gave me a just a minute’s break from it all so I could focus and get back into it.
DS2 - Again it was brilliant. But I’ve got a bit of a loose clicky jaw and I bit down too hard and dislocated it. It took me a good few hours to get it to click back into place properly.