The TVS will protect against excessive voltage provided the current is limited to a suitably small amount but it will not protect against the polarity reversing. For example, if the TVS clamps to ground it will try to prevent the voltage exceeding +5V and -5V so you need to be certain circuits connected to the 5V will not be damaged is the positive and negative are swapped over.
A TVS is a clamping device, it diverts current through itself if the voltage across it is higher than its rating, therefore it has to handle all the power if the voltage is higher. You can use it to protect against 230V but bear in mind the other 225V has to be 'dumped' somewhere as heat. This is why it will only work if the current supply is small. If you intend to protect against a 5V device being connected directly to 230V AC you should look at methods to prevent the connection instead.
Brian.