Google Sites is a growing, changing platform that continues to improve. Sometimes those innovations and those changes can cause problems with existing content.
For example, we had a client mention some problems with their website viewing on the iPhone. We troubleshooted the problem that day and fixed it that day. Even before Google knows about an issue with Google Sites, we are on the job fixing the bug or at least reconfiguring the website as a work around.
With your Google Sites website, you are investing in stability. Your website will be up 99% of the time and your content will remain compatible across browsers, devices, and updates. It's liberating.