I'm a big advocate of gzipping the web. People should be aware that enabling gzip can cause some differences with page rendering due to the extra decompression step. It also increases CPU load on the server. There can be other minor issues too. No show-stoppers though.

Also, the percentage of compression savings should not be confused with the savings in load time. An 80% reduction in the size of the response does not mean an automatic 80% reduction in page load time.