The Auto-Correlation function of Walsh-Hadamard codewords does not have a good characteristics.
It can have more than one peak and thus, the Walsh-Hadamard codes do not have the best spreading behavior or correlation property.
The cross-correlation function of the Walsh-Hadamard codewords can also be non-zero for a number of time shifts and unsynchronized users can interfere with each other.
Which other codes or sequences show :
A good auto-correlation attribute? Good Cross-correlation Property ?