It's the same design style than Google+ and other new changes have. It's a logical step and Google will apparently transfer every service to the new design. Some people complaining about a slower experience.
I'll guess that the site is optimized for Chrome. Lately using Google-sites with Firefox getting slower and slower.
The design is modern and functional. Looks like that's the new way Google is heading.
Update: All images are in WebP. If you use a browser that doesn't support this, it will take up to 10x longer to load because the fallback is PNG
See this post for more: The redesigned Google Play Store
