I know one little guy born at 25 weeks, he has chronic lung disease, which was diagnosed not long before he went home from hospy.
I also know one born at 26 weeks, who is fine, and one born at 27 weeks, also fine.

Shades made a good point about the balance and coordination issues. It comes from a lack of core strength because the baby spends time lying down, rather than all curled up, so those core muscles develop differently.