I have recently come across a situation where I need to determine whether an account is locked or not.
Conveniently, the IADsUser interface provides a property that is exactly what I need !.
This little code block will return a true or false depending on whether the account is locked or not, with true representing a locked account.
var objUser = GetObject("LDAP://cn=user,ou=users,dc=example,dc=com");
var boolUsrLocked = objUser.isAccountLocked;