Feels GREAT! Happy to be using this in addition to Safari. I also added uBlock Origin as an adblocker but would still love if FF eventually included native, declarative content blocking like Safari (probably less likely given how much money they get from Google).
Firefox includes Tracking Protection, which, as it says on the tin, blocks trackers, not ads. But many, many ads have trackers built in, so it practically also blocks most ads. This is default-enabled in Private Browsing. To enable it in normal browsing, you can toggle privacy.trackingprotection.enabled in about:config. I think, there's also now a GUI toggle in the settings to do that, I haven't checked yet. And well…
Regarding engines, Chrome uses Blink, as opposed to WebKit. They were forked a couple years ago.