DD is an only child and whilst its lovely for the most part, there is a little bit of me that wishes we could have had more. She well adjusted, not spoilt (I'm even more strict on her to prevent comments about spoilt only children!) and is a credit to her parents, if I do say so myself! There were times when she was younger, when it was bloody hard work to entertain her. For example, where parents can tell their kids to just 'play' for a bit, whilst you relax, you can't do that with an only child. They need company and on a wet day in January, you're all they've got.
Its also sometimes hard work, because one of the parents is 'left out', so to speak. I mean, you see a family of 4 walking down the road and mum's got one and dad's got the other. In our family both me and DH vie for pole position!
OTOH, When I've got dd time, DH is free to do his thing and vice versa!
The only thing that worries me now, is one day DH and I won't be here or will need help from our dd, as inevitably happens as you go into old age! The onus will be completely on DD to tend to our every need, without the help or support of a sibling.
I appear to be rambling now! Hopefully you can pick the bones out of what I'm saying though! DD is 12 now, btw.