To add some important points:

> uMatrix is a replacement extension from the creator, and compatible with, uBlock.

To avoid any confusion, I think the parent means, 'from the creator of ... uBlock'. uMatrix is not by the creator of NoScript.

Also, blocking just JavaScript is quicker and easier in uMatrix (at least easier than the current NoScript; I don't know about the upcoming version). The UI is far more efficient, and you configure it by origin/remote pairs (e.g., on foo.example.com allow googleapis.com; on other example.com hosts, block it; on example.org allow it everywhere).

But NoScript does far more than block JavaScript; it's a sophisticated firewall, in some ways. Look through the options menus and lookup the features, such as ABE; it's impressive. uMatrix doesn't replace much of that functionality.