Hmmmm I tried Quantum on Nightly and again yesterday as a release. Bookmarks were in the top left. As for add-ons, I only needed uBlock and that has been ported to WebExtensions.
But the speed increase is quite perceptible. My plan is, I'll stay on the Moon until I replace my machine, and then I'll move to Quantum full-time.
There is some usrChrome.css code I use to place the tab bar underneath the address bar. But I like the Photon interface.