well I think they were difficult but in different ways - they certainly seemed that way compared to others perfect babies!
DS had colic and screamed the place down daily from 4pm til midnight until he was at least 5 months old. there was just no consoling him. he was my first baby, it was horrible, i ended up with PND. and when he was a little older he could never play independently, he needed you all the time. in fact at 5 he still does this to some extent.
DD has never slept well. she is now nearly 2.7 and i can count on one hand the number of times she has ever slept through the night. she would never be put down, hated being flat and would only settle to sleep on me, upright on my chest, in a sling or through feeding. i fed a lot! we are trying to gradually get out of co sleeping now that the new one is on its way but being met with much resistance. despite being practically permanently attached to me for 2.5 years she is actually a very independent little girl now.
actually thinking back to how they both were as babies i think we must be slightly mad having another!