Greasemonkey 4 For Users

As mentioned in the main post, Greasemonkey 4 is changing how it runs user scripts.  Many user scripts will continue to run as expected, but this will break some scripts.  If you rely on such scripts, you might want to install Violentmonkey or Tampermonkey, both of which provide better compatibility for existing scripts.

Scripts

If you'd prefer to stick with Greasemonkey, you'll need to wait for the script to be updated to be compatible.  Find the original author of your script, and ask them to update for Greasemonkey 4 compatibility.  Referencing this post may help.  And please know that we'll continue working to improve further and further as time goes on!

Features

Due to the external deadline (when Firefox 57 comes, Greasemonkey 3 won't work anymore) not all features you're used to are available.  For example: Firefox Sync and script auto update are missing.  There are no per-script settings (custom include/exclude), and some of the UI is still quite basic.  This as well will be improved in the future.

We welcome feedback, reach out via the greasemonkey-users discussion group.  Please also keep in mind the volunteer nature of this open source project when doing so!