As for those of you new to PS4 Dreams... Why not check out some of Media Molecule's videos? Since Dreams is a creation tool, it's not something you can easily describe to someone without showing it to them. The possibilities are nearly endless in Dreams, and because of that it has something for everyone. You can create, music, movies, novels, classic styled arcade games, escape rooms, horror games, platformers, RPGs, racing games, walking simulators, and so on. If you can Dream it, you can create it... And if you can't Dream it for yourself, that's where the community and last year's beta comes into play. Dreams is already populated with thousands of amazing creations, and now it's just up to you to discover them -- later this week that is.
If you want to know more about Dreams, I also recommend checking out the YouTube channel Project Genesis. This guy is pretty great, and has spent the last year covering a lot of the amazing creations out there. If you want to know more about what Dreams is and what you can make with it -- his channel is the one you want to watch.
Check out two of his newer videos below (I really recommend the horror one):