Has been absolutely brilliant.
DD was 6 and 2 months and DS1 almost exactly 4 when DS2 was born.
They've been fantastic. DD felt a little pushed out initially but is much closer to dh as a result and I do try to spend time just with her.
It's been the making of DS. - he's obviously matured over the last year anyway, but he suddenly seemed much less anxious and introverted when DS2 was born. I think he naturally finds being centre of attention or singled out difficult. He's no longer the youngest, and whereas before he would run and hide when grandparents and so on were questioning him or giving him full-beam attention, now they are more chilled, he has come out of his shell a bit.
With regards to day to day stuff, he's been out with me on the school run since he was born. Initially sleeping on the way there and back. Now doesn't sleep, but happy to be fussed over by DD's friends. For the first year DS1 was still at home 2 and a bit days a week as was at pre-school. Now he is at school full time.
DS2 meanwhile is the jolliest smiliest baby. He loves his older siblings, and they are exceptionally good with him - yes they get annoyed when he wrecks their lego, but not aggressive or cross. He makes them laugh. And they're great at making him laugh too.
The only things that bother me (well, not bother, but that make me think my goodness, is easier with 2 close in age) are things like potential holidays. We're putting off the big adventure holidays we were thinking about until he's older, which is a shame for the older 2. Would like to go skiiing, but would like all of us to be able to ski or at least try - hard to do when one can't walk yet. And of course, so many family tickets for attractions and things are really only for 2 adults and 2 children.
But I can honestly say that it was the best decision we ever made.