It's nothing incredible, really I don't want you to be underwhelmed if you try it out. It's mainly a lockscreen and notification shade replacement. It's interesting and possibly useful, it is to me. On the notification shade you have 2 tabs, the ALL tab and the KEEP tab. If you left swipe the notification gets deleted. If you right swipe the notification gets moved to the KEEP tab and you can address it later. Just this little functionality I love because it lets me organize my notifications based on if I can get to them there, or if I want to save them for later, and removes a lot of clutter.
One of my favorite "features" is no more swipe screen, hehe. Actually this is almost definitely a bug and I'm sure they will eventually fix it. Normally even if you don't have to enter in a security pin/pw/fp you still have to swipe, which is kind of stupid IMO and an annoying extra step to turn on your phone. For some reason Goodlock takes that away, and if you are in a trusted area/device, etc then when you turn on the screen there is no swipe screen, just whatever you were on when you last turned it off. Once your security period runs out then it goes back to whatever security lock you had on it, so it's still safe in case you lose it or someone else picks it up.
One thing that is mixed is the appearance, Samsung tried to really copy the stock Android look. Honestly I think Samsung's notification shade, icons, etc are much nicer looking that Googles and IMO they took a step backwards by making it appear like vanilla Google. You can change the color scheme, although it's a bit clunky to do so. You also get routines, which means you can setup your lockscreen and notifications certain ways, then only have those routines be true based on location or time. Definitely interesting.
