dropping in from the russian boards to add some bonding info., if you don't mind.
our little girl was in a pretty bad situation in russia, she was hospitalized her whole time in russia (10 months) and came home at 11 months. she was sick and malnourished, basically had little to no stimualtion on a daily basis, yet her bonding process was quick and easy. we were very prepared and did do attachment parenting to foster her bonding, but we truly had no issues with it.
last year we adopted our little boy at 7 months from a great orphanage in russia, where he had a decent amount of food, was used to being held (they even held him while bottle feeding him~very rare), and had all sorts of stimulation~toys, mirrors, ball pit, swings, etc. probably one of the best orphanage situations possible. very loving caregivers, with a small ratio of babies per caregiver. (4 to 1, 24/7.)
however, he had a tough time bonding to my dh. it took almost 1 year for him to accept his daddy. i feel he probably felt some grief for the loss of his former life, even though he was a young infant. he had very anious attachment to me and his first 6 months home were very rough. (and we were experienced at this.) we worked through it and he is now securely bonded to us and his whole family.
based on my personal experience, i feel the baby's personality will play a huge role in the bonding process. based on the foster care situation in Guatemala, there are probably far fewer babies that suffer through a longer and harder attachment process, but some will and do. our daughter has a strong and outgoing personality, she is not afraid to try things and i believe this helped her survive her early days. our little guy is very emotional, he takes everything to heart. we joke about hurting his baby feelings all the time because he is so sensitive. (even his almost 4 year old sister will ask if his baby feelings got hurt when he starts whining.

)
as for not sharing the fact that the child is adopted,

, my kids think all babies are adopted and come from russia. boy, do i have some explaining to do.

we have shared their stories with them since we brought them home. it is part of them and it can not be changed.
good luck in your journey.
ps~ dh saw a woman at work today with 2 little girls adopted from China~commented on how beautiful they were. so, the man who said one child is now thinking of his 3rd adopted child.