The new Google Calendar design is a lot sleaker, cleaner. "Quick add" is now available if you click the arrow next to the "Create button" (not very intuitive), "Print" and "Refresh" are now buttons instead of links, the month view below the "Create" button can be collapsed, "Save" and "Discard" buttons are only displayed at the top of the page.
"Right now, the changes are just cosmetic and haven't affected the way Calendar works. You can choose to turn off the new look by clicking the gear icon and choosing Use the classic look (you can turn it back on by going to the gear icon and choosing Try the new look)," explains Google.
Here's few screenshots of new google calendar:
[Source: Calendar Support, Thanks, Andrew, Alex]