I found out I was expecting DD when DS was just 6 months old. It was a real shock. I wasn't ready for another baby. I did go through a phase at the beginning thinking I actually really wished I wasn't pregnant. Ofcourse after seeing scans etc I fell in love. These are the only negatives I can think of, other than the overwhelming GUILT that DS had to share me when he was so so young.
Positives; They ADORE each other, honestly I could disappear and as long as they were together I don't think they'd be bothered.
The nappies were a nightmare but it only lasted 18months and they potty trained at the same time, so went from about 16-20 nappies a day to 0, was bliss!
DS learned at a very early age to be gentle with other people, DD has alot of confidence as when she was forming bonds with other little ones for the first time her big brother was right there with her, so she just gets on with people no problems.
They are both patient (well.. for kids) and realise that other people are important.
If all had gone to plan (ie. me going back to work this sept and not being pregnant again! hehe wouldn't change it for the world)then they would have been at full time school within a year of each other and it would have made returning to work easier.
At 15months you are still in baby mode so don't have to try and remember what to do with one (I'm scared that I've forgotten everything this time) and will not have to spend ££'s on baby items.
So although I was rather devestated when I first found out, I honestly, honestly wouldn't change it for the world.