Circles was Google+'s most touted feature. It enabled users to quickly manage the different groups in their lives and offered an intuitive interface for sorting their contacts. Still, any sort of contact management is a chore so any improvement to the feature is welcomed.
The Circles page has gotten several
improvements to make it work better on smaller screens and also make it easier to find contacts, via the quick access link to your email address books.
Another big addition is the left-hand navigation bar which makes it easier to switch between circles and also brings the feature in line with Google's standard design ideas.
The second new feature is the new Find People, which has been revamped. It also features the new left sidebar, but it also makes it easier to find pages or people to follow based on your current interests.