Most Gmail users won't be impacted by the changes, unless of course they are against change.
If you want to see the new look click on "switch to the new look" that will appear soon on the bottom right of your Gmail screen.
Most of the changes are about customization. If you don't change something yourself, not much will change.
Here's the basic rundown from Google:
- Instant messages (Google calls them conversations) now comes with photos and the messages have a better streamline like a real conversation.
- The left hand navigation panel is now more customizable
- Gmail will fit all screen sizes
- Better search function
- Theme pages now have better background imaging
Google produced a video to explain the changes.