With the upgrade to 2.16, PolyGerrit will become the default UI.
PolyGerrit is a rewritten UI based on Polymer  in Gerrit that is available from Gerrit 2.14, you can access this through ?polygerrit=1 or using the footer where it says "Switch to New UI". Note that you can still switch back to the old ui by doing ?polygerrit=0 (or again using the footer).
The New UI is polished under 2.16 and implementing a lot of missing features such as project dashboards and the inline editor. PolyGerrit under 2.16 also redesigns the layout with new colours and styles! It also helps new users with creating there first change!
A date has not been determined yet on when to upgrade, though a suggestion is for after the WMF Hackathon .
(This upgrade will be large and will also make the UI modern by default, encouraging new users to contribute and also users who left due to the ageing UI).
 https://www.polymer-project.org  https://phabricator.wikimedia.org/T200739#5165755