I like the implementation of this app. No menubar, just a little window that pops up when activated, which has five options:
show processes running, close all apps, shutdown, hide all apps and show all apps
Sure, you can get all these things with one obscure key stroke combination or another, but I like the handiness of this (and not having to keep track of additional keyboard combinations.
No preferences either. Very minimalistic.
Not enamored of MAS-only apps, but developer's choice (and I am guessing it will be charged for, too, at some point, like same developer's other app, OneTrash).