Yeah my DD went through a crappy sleep phase at around 6mo, I think it's pretty normal. DS is a pretty decent sleeper but wakes at least 2 or 3 times a night. He's had a rough run with illnesses and feeding issues though so we just deal with it as best we can. It's tough when I'm up for the third time that night from 3:30-4:30am to feed & resettle him then DD is up and asking for breaky at 6!
I think parenting small children gives you a whole new appreciation for the magical wonders of sleep.