The interface does not really need explaining, as it is just unmodified Firefox. For those not familiar with vanilla Firefox, it is very similar to Chrome: tabs at the top, then address bar with navigation on the left and extensions and settings on the right, then a bookmark bar below that. The new tab page is just a search box with your search engine of choice, to which you can add shortcuts. The browser is compatible with Firefox extensions and has uBlock Origin preinstalled.

On the LibreWof website, the developers identify their mission as supporting prvacy, security, and user freedom. It is this third category that is most interesting, as it may run afoul of the law. LibreWolf claims to disable DRM (Digital Rights Management), a technology used for securing copyrighted material and sensitive information. The circumvention of DRM is illegal in many countries including the United States, where it is prohibited under the DMCA (Digital Millennium Copyright Act). However, it is still fully legal to use the LibreWolf browser. 

The other two aspects of its mission are fully above-board, and it seems to accomplish them well enough. The browser is open-source, and has a very good privacy policy. I did log many queries to Mozilla domains while using the browser, so it appears that some of their telemetry remains in the browser, despite the efforts of LibreWolf developers to remove it. LibreWolf also claims to have very stong fingerprinting resistance due to having enabled RFP, but a test on Panopticlick revealed a "unique fingerprint". This is the same score that Vivaldi received, and like Vivaldi, LibreWolf's score appears misleading. whatismybrowser.com was unable to distinguish it from vanilla Firefox (a very common browser, so it is hard for sites to track you based on this information), and I got a security alert from Google while using it claiming that I had signed in on a Windows PC (I don't have a Windows PC).

As for functionality, LibreWolf does quite well. I didn't encounter any rendering errors, and page load was very snappy. The fingerprinting resistance does have some quirks, such as blurring text on Google Docs, but it can be disabled on a site-by-site basis if necessary. One feature that I really missed while testing LibreWolf is password autofill. It simply doesn't exist. Considering that the browser logs you out after every session and clears cookies, signing back in without an (often expensive) external password manager is a real pain, especially if you use 2-factor authentication. This has the unfortunate effect of deterring users from properly securing their accounts, which somewhat defeats the point of a security browser.

Overall, I can't really recommend this browser to anyone. It is a product without a market.  If you want to get rid of Firefox telemetry, use Waterfox or Arkenfox. If you want an easy user experience, use something like Arc or Brave. And if you want great security, use Tor. There is really no reason to install or use LibreWolf.