For longtime Firefox users (and Chrome as well), Waterfox's interface will look very familiar. At the top is a Chrome-like tab bar instead of Firefox's floating tab style (which you can get by using any third-party theme), and below that, an exact copy of Firefox's toolbar. The new tab page has a search bar, shortcuts, and an optional recent activity panel, basically identical to Firefox. Waterfox has more customization, with an extra section in settings for changing the interface. 

Unlike Firefox, Waterfox can install Chrome extensions and Opera add-ons in addition to the Mozilla add-ons library. This allows for greater flexibility and more extension options, as many extensions are only made for Chrome.

In terms of privacy, Waterfox does quite well. It collects no telemetry data, so only you know your browsing history. Its privacy policy is very clear on what data it collects (which is the bare minimum needed to operate the browser). The browser has a tracker blocker very similar to Firefox (with the same interface and probably the same code), which blocked 9 trackers on weather.com to Firefox's 8. I think the difference is probably in the blocklists used. For comparison, Brave blocked 10. Neither Waterfox nor Firefox blocked anything on google.com. When tested on Panopticlick, Waterfox was found to have a 'unique fingerprint', but otherwise has 'strong tracking protection'. These results are very similar to Firefox.

Waterfox has most of the same integrated features as Firefox, with the exception of Pocket and news (Snippets).

Overall, Waterfox is a pretty good browser. I would recommend it for people looking for a private browser without a lot of bells and whistles.