I had my mother as my support person for my first two births (for various reasons I won't go into here) and my DP (of just over a year at the time) at my third.
My first two births were horrendous - I yelled at screamed at my mother every time she tried to encourage me or soothe me and I just wanted her to go away. My third birth was calm, quiet and quick ... during labour, DP and I watched TV, joked, laughed. It was a totally different experience. I know subsequent births tend to be quicker (but my labours have been prolonged each time), but my mum had told my DP what to expect from me (and of course none of it happened) and it was all over so quickly, I kinda felt like he had missed out on something.

But having him there was a truly special occasion and I wouldn't have it any other way (thankfully neither would he - I couldn't stand to have my mum or his mum there!)