My daughter used to sleep through the night. Now she is teething.
All kids are different.. My daughter is 3 months now and sleeps 8-10 hours a night. She doesn't cry without proper reasons (either hungry or sleepy) but really loves to be carried around during the day.
Who knows, maybe my next one will have colic and be a complete nightmare.
She doesn't sleep through the night any more. Luckily, she still goes back down pretty quickly but I'm not looking forward to the day when we try to pull the bottle from the crib. That will be bad.