Wise stopped offering patch files, so each release is a full installer. You can get away with installing it to your SP2 install, but you will have to re-enter your serial numbers and basically go through the normal setup process, so my own personal preference is to perform an uninstall of the old version and then a clean install of the new version. If you have a server install in a shared environment, you need to make sure that all users are logged out when you upgrade. You also need to reinstall any clients.

The Wise Share Point remains unaffected, but as with all major operations, a full backup is always a good idea.