as above.
from my experiences, it seems easier to get along with colleagues
in a small company cos everyone knows eachother and understand
their character.
whereas in a big company, chances are, u only know the people in
your own department. heck, i even came across people who don't even
don't know people from their own department. 
secondly, even if u know others from other departments but only
sees them once in a while. u'll never know what their characters
are. for example they might smile at u, talk and laugh together but
once away u will never know that they might start talking bad about
u behind their backs.
feel free to give comments and share your experiences. 