The new interface is more colorful and uses more images. There's a hamburger-style menu, a section that shows your stats and the badges you've earned. You can select 2 to 5 languages, including a few languages that aren't yet available in Google Translate like: Cantonese, Cherokee, Corsican, Tibetan, Guarani, Hawaiian and more. Then you only need to translate some phrases or rate translations.
Google also offers a simplified version of the Translate Community site, which uses the old interface.