As some of you have been aware there is a new UI called PolyGerrit. This will be made the default UI. You doin't have to worry as you can switch back to GWTUI if you want to take your time getting use to PolyGerrit. (Use https://gerrit.wikimedia.org/r/?polygerrit=0 to go back to GWTUI).
PolyGerrit is a rewritten UI that is based on the Polymer framework in pure html and js!
Internet Explorer support is discontinued in the New UI, so you will have to use the old ui or try using Firefox/Chrome/Chromium.
Browsers that are supported are: Safari, Chrome, Firefox, Microsoft Edge, Opera and any Modern browser.
Zuul integration will be more close in PolyGerrit. You can use the zuul-status plugin to display the zuul status for your gerrit change
right on your gerrit patch.
Note: Gerrit 2.16 is the last from the 2.x serias and the last release to have GWTUI. Gerrit 3.0 drops GWTUI.