We adopted two young toddlers, and it has been a wonderful experience, but the others that have posted make a lot of very good points. I count us VERY lucky that both of our children have adjusted and bonded so well.
In our case Lauren came home at 11 months old, and Daniel came home 3 months later at 20 months old. I am SO glad that they did not come home at the same time, and for that matter, that Lauren came home first. Being younger (or just her personality) she bonded with us relatively quickly, but we had a LOT of sleep problems for the first 6 weeks or so, and if Daniel had been home, I don't know what I would have done. By the time Daniel came home 3 months later, we had had a chance to really get to know Lauren, and her us, allowing me to focus more on Daniel. I think that the fact that they are close in age worked out to our advantage in that they are kind of like twins (though there definetly is a developmental difference) and they have a lot of the same needs, as opposed to having an infant and a toddler.
Not sure if my ramblings helped, but there is my 2 cents worth!
If you have any specific questions, feel free to PM me.