What you gain when switching to the new version of Google Sites:
- Better handling of third-party embed codes. The old version of Google Sites is notoriously finicky when it comes to embedding media from sources outside of the G Suite ecosystem. The new version of Google Sites is much improved in that area.
- Design templates optimized for phone and tablet viewing. The old version of Google Sites does have a "mobile-friendly" option hidden in the settings but even that with that setting enabled old Google Sites don't always function correctly on mobile phones.
- Streamlined integration of docs, slides, forms, spreadsheets, videos, and other files stored within your Google Drive account. You've always been able to include these items in Google Sites, the new version just makes it a little easier to do.
What you lose when switching to the new version of Google Sites:
- Page-level permissions. This feature lets you give students access to edit specified, individual pages within a site. So far this feature has not been added to the new version of Google Sites.
- "Announcements." The "announcements" page format in old Google Sites essentially enabled you to create a blog section within your site. This feature has yet to appear in the new version of Google Sites.
Google hasn't announced a firm deadline for when they're ending support of the old version of Google Sites, but it's going to happen sooner than later. If you're thinking about using Google Sites for the next school year, you should use the new version to save yourself headaches down the road.