The level creator is simplistic but very easy to use, I spent about an hour and a half in total just creating. The exploration I did was motivated by finding good places to connect those creations to; while I was doing that, I personally enjoyed seeing some people attempt to create a sense of continuity by linking worlds with a similar look or feel together, though with such freedom comes quite a few chaotic levels that are difficult to navigate and will probably end up overwhelming those.
So navigating through the chaos to find a scenic spot to connect my own to was how I chose to play.
But whatever you choose to do, it's a novel gameplay loop. Going deep into the labyrinth of custom dreams made by all sorts of people, to add your own section, expanding it more and more, and only leaving to build your next addition.
I only stopped due to an issue where the web client froze, forcing to me to refresh, and be barred from continuing by a message on the login screen: "too many login attempts".
I've made three worlds(for now) and connected them quite closely to each other in the 'blue' category, if you're interested in finding them, and know what I mean by that (hint: not light blue!).
If this is to receive updates in the future I'd love to see an expanded level editor and perhaps a downloadable client. I really enjoyed this.