I have two lads, aged 2 years and 4 months.
Both my wife and I were quite keen to have kids and since we met in our thirties then we felt we couldn't hang around too long before trying for them.
Douglas, the elder of the two, is particularly lovely at the moment as he has become very affectionate enjoying kissing and cuddling his dad and his baby brother. He is like an open book, when he is annoyed he flies into wild rages, when upset his lips tremble and streams of tears pour down his face, and when he is happy his face lights up and he laughs like a drain. It is quite a nice change from adults who tend to hide their feelings!
Anyway, there are pros and cons. The cons at the moment are that my wife and I are very active people, who used to spend just about every weekend hill walking or scrambling. Now it is difficult to do anything. Also, we have loads less money as the combination of maternity pay and nursery fees and deposits have massively reduced our disposable income. Finally, it does put strains on your marriage in that you are both tired and stressed, at least with young kids, and you have to be alert that you are doing your fair share of the work.
The pros are more intangible I suppose. After all kids aren't possessions to be paraded and they often aren't even nice to be around. If anything they can be very wearing. But you do get the virtuous feelings associated with devoting yourself to unconditionally loving and caring for someone who is totally dependent on you. And in lots of ways your priorities change as a parent and you get a different point of view of the world (for example my best mate, an enthusiastic non parent, seems very materialistic to me and a total spendthrift, although he has always been like that so I suppose it is just that I have changed).
My wife and I often miss our 'past life' - in some ways it feels like we have had to put a lot of our hobbies on hold during some of our prime years - but I think without the kids it would just get boring in the future, doing the same sort of stuff over and over.
And I am looking forward to teaching the lads to ride their first bikes and taking them climbing!